Iambic pentameter is a rhythmic pattern used in traditional English poetry and plays. It describes the beat or meter created by the words in each line. Meter is measured in small groups of syllables called feet. The word "iambic" means the foot used is an iamb, which in English has an unstressed syllable followed by a stressed syllable (like in "a-BOVE"). The word "pentameter" means each line has five of these feet.

Iambic pentameter is the most common meter in English poetry. It was first used in English by Geoffrey Chaucer in the 14th century, inspired by French and Italian poetry. It appears in many important English poetic forms, such as blank verse, the heroic couplet, and some rhymed stanza forms. William Shakespeare used iambic pentameter in his plays and sonnets. John Milton used it in Paradise Lost, and William Wordsworth used it in The Prelude.

Lines in iambic pentameter usually have ten syllables, making it a type of ten-syllable verse.

Meter

An iambic foot is a pattern of rhythm made up of an unstressed syllable followed by a stressed syllable. This rhythm can be written as:

A standard line of iambic pentameter has five iambic feet in a row:

Examples of this rhythm can be heard in the opening line of William Shakespeare’s Sonnet 12:
When I do count the clock that tells the time

and in John Keats’s ode To Autumn:
To swell the gourd, and plump the hazel shells

This rhythm can be written using a "/" to mark stressed syllables (beats) and a "×" to mark unstressed syllables (offbeats). A standard line of iambic pentameter would look like this:

The word "iamb" originally described the rhythm of classical poetry, where rhythm was created by alternating short and long syllables. In English poetry, rhythm is created by alternating unstressed and stressed syllables. An English unstressed syllable is similar to a classical short syllable, and an English stressed syllable is similar to a classical long syllable. When a pair of syllables follows the pattern of an unstressed syllable followed by a stressed syllable, that foot is called "iambic." For example, the word trapeze is iambic because it has two syllables (tra-peze) and the stress is on the second syllable (tra-PEZE). A line of iambic pentameter has five such pairs of syllables.

Strictly speaking, iambic pentameter refers to five iambs in a row. However, poets often change the rhythm slightly while keeping the iamb as the most common foot. For example, the first foot of a line may begin with a stressed syllable instead of an unstressed one (called an inversion). The following line from Shakespeare’s Richard III begins with an inversion:
Now is the winter of our discontent

Another variation is when a beat is pushed forward to create a 4-syllable unit: × × / /. In the line To be, or not to be, that is the question, the fourth beat is pushed forward.

A common change is adding an extra unstressed syllable at the end of a line, creating a weak or feminine ending. One of Shakespeare’s famous lines has a weak ending:
Shall I compare thee to a summer’s day?

This line also has an inversion in the fourth foot, following a pause (marked with "|"). A pause acts like a line end, and the extra syllable of a feminine ending may appear before it. Shakespeare and John Milton sometimes used feminine endings before a pause.

Here is the first quatrain of a sonnet by John Donne, which shows how he uses different rhythms:
Batter my heart, three-person’d God; for you
As yet I can take no thought, but that my soul
Is like a stone, or like a metal, cold,
Or like a dead man’s flesh, or like a grave.

In this example, Donne uses an inversion in the first foot of the first line to emphasize the word batter. The rest of the line follows a clear iambic pattern. In the second and fourth lines, he uses strongly stressed offbeats to slow the rhythm as he lists short words. The parallel rhythm and grammar in these lines highlight the contrast between what God does to him and what he asks God to do. Donne also uses enjambment (continuing a sentence without a pause) between lines three and four to speed up the flow as he builds toward his desire to be renewed. At the end of the line, he adds an extra syllable, which can be read as an anapest (dada DUM) or as an elision (a shortened pronunciation).

Percy Bysshe Shelley also used variations in rhythm in his Ode to the West Wind:
Drive my dead thoughts over the universe,
Nor let me loose upon the winds a sigh,
That may be heard by those who have been lost,
And know not what is lost, or where it is.

These examples show that iambic pentameter does not always consist of only iambs, nor does it always have ten syllables. Many skilled poets, like Donne and Shakespeare, change the rhythm to create more interesting patterns and highlight important themes. In fact, the ability to vary iambic pentameter may be what makes the work of poets like Donne, Shakespeare, Milton, and Edna St. Vincent Millay stand out.

Some scholars believe iambic pentameter has been important in English poetry because it contrasts with another common meter called tetrameter, which has four beats per line. Tetrameter is used in nursery rhymes, children’s songs, and folk music. It has a very regular rhythm, almost like a repeated tune. In contrast, iambic pentameter has five beats per line and allows for more varied speech patterns. This flexibility lets poets use different speeds and tones, as seen in Alexander Pope’s An Essay on Criticism:
When Ajax strives some rock’s vast weight to throw,
The line, too, labours and the words move slow.
Not so when swift Camilla scours the plain,
Flies o’er th’unbending corn, and skims along the main.

In the first lines, words like Ajax and rock’s vast weight are slow and heavy, while in the second lines, words like Camilla are quick and light.

The last line of Pope’s example is an alexandrine, a line with six iambs (iambic hexameter). It is sometimes used in iambic pentameter poetry as a variation, especially at the end of a passage. Pope also used contractions (shortened syllables) to create a faster rhythm in his work.

Iambic pentameter allows important words to be stressed at different points in a line, as long as they follow the pattern of unstressed and stressed syllables. Unlike tetrameter, which has a steady rhythm, iambic pentameter lets poets vary the pace and intonation of their speech while still keeping a regular meter.

Theories of iambic pentameter

Linguists Morris Halle and Samuel Jay Keyser created the first theory of generative metrics, a system of rules that explains which variations are allowed in English iambic pentameter. According to the Halle–Keyser rules, only "stress maximum" syllables are important for determining the meter. A stress maximum is a stressed syllable that is surrounded by weak syllables in the same sentence and line. For a line of iambic pentameter to be acceptable, no stress maximum can appear on a syllable that is normally weak in the standard, unchanging pattern of iambic pentameter. In the line from John Donne, the word "God" is not a stress maximum because it is followed by a pause. Similarly, the words "you," "mend," and "bend" are not stress maxima because they are at the end of lines, which is necessary for rhyming between "mend/bend" and "you/new." When the Donne quatrain is rewritten to show stress maxima (marked with an "M"), it looks like this:

The Halle–Keyser system has been criticized because it sometimes identifies prose as iambic pentameter. Other scholars later revised the theory, and together with Halle and Keyser, they are known as "generative metrists."

Later generative metrists noted that poets often treat multisyllable non-compound words differently from single-syllable words and compound words. Normally weak syllables can be stressed if they are single-syllable words, but not if they are part of multisyllable words, unless they appear at the beginning of a line or phrase. For example, Shakespeare wrote in The Merchant of Venice, Act I, Scene 1:

Shakespeare used few lines like "As gazelles leap a never-resting brook." Both lines have the same stress pattern, including the normally weak third syllable being stressed. The difference is that in Shakespeare's line, the stressed third syllable is a single-syllable word, "four," while in the other line, it is part of a two-syllable word, "gazelles." (The rules and exceptions are more complex than described here.) Pope followed this rule strictly, Shakespeare followed it fairly strictly, Milton followed it less strictly, and Donne did not follow it at all—which may explain why Ben Jonson once said Donne deserved punishment for "not keeping of accent."

Derek Attridge has noted that the generative approach has not helped explain why certain metrical forms are common in English, why some variations disrupt the meter while others do not, or why meter is so powerful as a literary tool. Generative metrists also fail to recognize that a normally weak syllable in a strong position may be pronounced more strongly, making it no longer "weak."

History

It is not known exactly where this meter originated. However, in the 19th century, a Swiss scholar named Rudolf Thurneysen suggested that it developed from the Latin hexameter. This is because there is a common type of hexameter with two stresses in the first half and three in the second. For example:

"at páter Aenéas, audíto nómine Túrni"
[but Father Aeneas, when he heard the name of Turnus, …]

"íbant obscúri, sóla sub nócte per úmbram"
[they were walking slowly, beneath the lonely night through the shadow]

A 3rd-century Christian African writer named Commodian wrote in an irregular style of hexameter. He used a version with five word-accents. Thurneysen quotes:

"irásci nolíte / sine caúsa frátri devóto recipiétis énim / quídquid fecerítis ab íllo"
[do not be angry without cause at a devout brother; for you will receive back from him whatever you have done]

When Latin pronunciation changed to French, many words had fewer syllables. For example, "illa venit currens" ("she came running") became "la vint corant" in French. Similarly, "audite, seniores" ("listen, sirs") with seven syllables became "oez seignurs" with four. Final syllables in French were often lost, unlike in Spanish and Italian.

The accentual Latin hexameter shares a feature with iambic pentameter: the position of the first and third accents is not fixed. For example, the first accent can appear at the beginning of a line or in the second position, as in pentameter.

Possibly the earliest example of iambic pentameter is the poem Boecis ("Boethius"), written in the Occitan dialect of southern France around 1000 AD. An example is:

"Bella's la domna, e'l vis a ta preclar,
Davan so vis, nulz om no's pot celar;
Ne eps li omne, qui sun ultra la mar"
[Beautiful is the lady, and her face is so bright,
Before her face, no man can hide himself;
Not even those men, who are beyond the sea.]

In this meter, each line has two halves. The first half has four syllables, but sometimes an extra unaccented syllable is added after the fourth. The second half has six syllables.

This optional extra syllable, as well as an extra unaccented syllable at the end of a line, is also seen in the 11th-century French poem La Vie de Saint Alexis. An example is:

"De la dolor, que demenat li pedre
Grant fut la noise, si l’entendit la medre:
La vint corant, com feme forsenede,
Batant ses palmes, cridant, eschavelede;
Veit mort son fil, a terre chiet pasmede."
[Of the grief, which the father was showing,
Great was the noise; the mother heard it;
She came running, like a frenzied woman,
Beating her palms, crying, dishevelled,
Sees her son dead; falls fainting to the ground.]

The earliest Old French chansons de geste (epic poems) from the 11th to 13th centuries were also written in iambic pentameter. These poems usually had a pause after the fourth syllable. One of the oldest is The Song of Roland, which begins:

"Carles li reis, nostre emperere magnes
Set anz tuz pleins ad estet en Espaigne:
Tresqu'en la mer cunquist la tere altaigne.
N'i ad castel ki devant lui remaigne;
Mur ne citet n'i est remes a fraindre,
Fors Sarraguce, ki est en une muntaigne."
[Charles the King, our great Emperor,
For seven full years has been in Spain;
As far as the sea conquered the high land.
No castle remains in his way;
No wall or citadel is left to break,
Except for Saragossa, which is on a hill.]

In this version of the meter, each line has two halves. The first half has four syllables (sometimes five), and the second half has seven (sometimes six). The first half has two stresses, and the second has three. In some cases, the final weak vowel "-e" is ignored, such as in "nostr(e) emperere."

This line was used more flexibly by the troubadours of Provence in the 12th century, including Cercamon, Bernart de Ventadorn, and Bertran de Born. In Old French and Old Provençal, the tenth syllable was accented, and feminine endings were common, making lines have eleven syllables.

Italian poets such as Giacomo da Lentini, Boccaccio, Petrarch, and Dante adopted this line, using the eleven-syllable form (endecasillabo) because many Italian words have feminine endings. They often used a pattern where the fourth syllable (normally accented) and the fifth (normally unaccented) were part of the same word, unlike the Old French line, which had a required pause after the fourth syllable. This pattern became typical of Italian poetry.

Dante's Divine Comedy, completed in 1320, begins:

"Nel mezzo del cammin di nostra vita
mi ritrovai per una selva oscura
ché la diritta via era smarrita."
[In the middle of the road of my life
I found myself going through a dark forest
where the straight path was obscured.]

Now, there is often no pause after the fourth syllable, and every line has eleven syllables. Another innovation in Italian poetry is synaloepha, where a final and an initial vowel merge into one syllable, as in "selva_oscura" or "via_era."

Giovanni Boccaccio's Filostrato from the 1330s, which inspired Chaucer's Troilus and Criseyde, has a similar rhythm. It begins:

"Alcun di Giove sógliono il favore
Ne’ lor principii pietosi invocare;
Altri d’Apollo chiámano il valore;"
[Some are accustomed to invoke Jupiter's favor
in their pious opening verses;
Others call on Apollo's power.]

The first English poet to write in iambic pentameter was Geoffrey Chaucer, who knew French and Italian and visited Italy multiple times. His Troilus and Criseyde

Reading in drama

There is a discussion among experts about whether plays like Shakespeare's were first performed with a clear rhythm or if the rhythm was part of how people spoke at the time. In both cases, when the lines are read aloud, they naturally follow a pattern called iambic beat. Experts say that Shakespeare's plays have few stage directions because the verse itself helps actors show what is happening. The way the lines are written connects to the actions the actors must perform.

In a 2000 production of Love's Labour's Lost by Sir Kenneth Branagh, the rhythm of iambic pentameter was highlighted in a scene where the characters tap-danced while delivering the "Have at you now, affection's men-at-arms" speech. In this scene, each iamb was matched with a tapping step.