Noah Webster
Pentameter
PENTAM'ETER, noun [Gr. five, and measure.] In ancient poetry, a verse of five feet. The two first feet may be either dactyls or spondees; the third is always a spondee, and the two last anapests. A pentameter verse subjoined to a hexameter, constitutes what is called elegiac.
PENTAM'ETER, adjective Having five metrical feet.