A line of verse with four feet is known as tetrameter (Greek
tetra, "four"). Tetrameter is second in popularity only
to pentameter in English.
Alternating lines of tetrameter and trimeter make up ballad stanza.
From the Guide to Literary Terms by Jack Lynch.
Please send comments to Jack Lynch.
Note: This guide is still in the early stages of development.
Three question marks mean I have to write more on the subject. Bear with me.