Pentameter (from Greek: - 'measuring five (feet)') is a poetic  meter. А poem is said to be written in (a particular) pentameter when the lines of the poem have the length of five feet, where 'foot' is a combination of a particular number (1 or 2) of unstressed (or weak) syllables and a stressed (or strong) syllable. Depending on the pattern of feet, pentameter can be iambic (one of three two-syllable meters alongside trochaic and spondaic) or dactylic (one of two three-syllable meters alongside anapestic) (see links below). This class of meters includes:

• the dactylic pentameter  of antiquity
• the iambic pentameter of the modern period