Decasyllable
Quick answer: A decasyllable is a ten syllable verse line, the ancestor of iambic pentameter and a staple of French and English poetry. Learn how the line evolved.
A decasyllable is a line of verse containing ten syllables. In French and other syllable-counting traditions, that count alone defines the line; in English, the ten syllable line almost always organises itself into five iambic feet, which is why decasyllable and iambic pentameter are close cousins rather than identical twins. The term keeps your attention on the syllable count itself, before any pattern of stress is assumed.
The distinction matters historically. The medieval French decasyllabe, the line of the Song of Roland, carried a fixed pause after the fourth syllable and no required stress pattern. When Chaucer imported the ten syllable line into English, the language's natural alternation of stress gradually pulled it toward the iambic grid. Watching that evolution is watching English metre being born.
How It Works
Count ten syllables and you have a decasyllable, whatever the stresses do. This invented line is decasyllabic and iambic at once: 'The ticket stub still marks the missing page.' This one keeps ten syllables but roughens the stress pattern: 'Somebody left the radio playing downstairs' has eleven, so trim it: 'Somebody left the radio on downstairs', ten syllables, and no tidy iambic swing. Both are decasyllables; only the first is comfortable pentameter. French practice adds a fixed internal pause, usually after syllable four, dividing the line into unequal breath-groups.
Where You Will See It
The Old French epics, including the Song of Roland, run in assonanced decasyllables. Chaucer's Canterbury Tales established the ten syllable couplet in English, and scholars still debate how strictly iambic his lines were meant to sound. In the sixteenth century the line hardened into iambic pentameter through Wyatt, Surrey and the sonneteers. Modern syllabic poets, including Marianne Moore's followers and many contemporary formalists, have revived pure syllable counting, writing decasyllables that deliberately avoid iambic regularity to keep a prose-like surface.
How to Use It in Your Own Poems
Writing strict decasyllables without iambic pattern is an excellent exercise in control: the count disciplines your lines while the free stress keeps them conversational. Try a poem where every line has exactly ten syllables and no two consecutive lines share a stress pattern. You will find yourself weighing every article and suffix, which sharpens revision instincts generally. Syllabic craft of this kind is quiet, but attentive readers hear it, and a judge scoring language notices lines that are exact without being stiff, something Writory's scoring rubric rewards.
What poets can take from this
- Count syllables on your fingers or in the margin; eyes alone will miscount.
- Decide early whether your decasyllables are iambic or purely syllabic, and stay consistent.
- Watch words like fire, hour and heaven, which can count as one syllable or two.
- Use a mid-line pause after the fourth syllable for a medieval French flavour.
- Revise by swapping any weak word for a same-syllable stronger one; the count holds the frame.
Try it yourself
Write a twelve-line poem in strict decasyllables about a hotel room the morning after a wedding, keeping the syllable count exact while letting stresses fall naturally as speech.
Questions
Is a decasyllable the same as iambic pentameter?
Not quite. A decasyllable is defined by its ten syllables alone, while iambic pentameter also requires five rising feet. Most English decasyllables are pentameters, but a ten syllable line with irregular stress is a decasyllable and not a pentameter.
Where does the decasyllable come from?
It emerged in medieval French and Provencal poetry, notably in epics like the Song of Roland, and entered English through Chaucer. Over the following two centuries English stress habits reshaped it into iambic pentameter.
By the Writory editorial team, reviewed by working poets. Updated July 2026.
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