pentameter

pentameter (pentăm'utur) [key][Gr.,=measure of five], in prosody, a line to be scanned in five feet (see versification). The third line of Thomas Nashe's “Spring” is in pentameter: “Cold doth / not sting, / the pret / ty birds / do sing.” Iambic pentameter, in which each foot contains an unaccented syllable and an accented syllable, is the most common English meter. Chaucer first used it in what was later called rhyme royal, seven iambic pentameters rhyming ababbcc; as Chaucer pronounced a final short e, his pentameters often end in an 11th, unstressed syllable. In his Canterbury Tales the pentameters are disposed in rhyming pairs. The pentameter couplet was used also by his imitators in Scotland, with the important difference that when the final e disappeared from speech the couplet became one of strict pentameters. This, known as the heroic couplet, became important in the 17th and 18th cent., notably in the hands of Dryden and Pope.

True wit is Nature to advantage dress'd,
What oft was thought, but ne'er so well express'd.
Pope, “Essay on Criticism”

Blank verse, a succession of unrhymed iambic pentameters, is primarily an English form and has been used in the loftiest epic and dramatic verse from Shakespeare and Milton to the present.

And, like the baseless fabric of this vision,
The cloud-capp'd towers, the gorgeous palaces,
The solemn temples, the great globe itself,
Yea, all which it inherit, shall dissolve
And, like this insubstantial pageant faded,
Leave not a rack behind. We are such stuff
As dreams are made on, and our little life
Is rounded with a sleep.
Shakespeare, The Tempest, iv:1

The sonnet is one of the most familiar and successful uses of iambic pentameter in English poetry.