In poetry, a pentameter is a line of verse consisting of five metrical feet:

Be what you can if thus your heart so deem,
For more the man will less the foible seem.

or

Where life expresses what it seldom feels,
It there less frequent intimation yields.

Lines are made up of five iambs and are called iambic pentameters. They contain ten syllables and five stresses. The iambic pentameter has been the basis for many forms of traditional poetry.