n. A poetic metre in which each line has four feet.
the GNU version of the Collaborative International Dictionary of English
n. A verse or line consisting of four measures, that is, in iambic, trochaic, and anapestic verse, of eight feet; in other kinds of verse, of four feet.
The Century Dictionary and Cyclopedia
Having four measures.
n. In prosody, a verse or period consisting of four measures.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. a verse line having four metrical feet
Word Usage
"The poem is written mostly in tetrameter, which is common enough."