In clasical poetry, a meter named for the Greek poet Sappho, used frequently by Horace and once in a while by Catullus (and by other poets, I'm sure). The meter consists of a four-line stanza, the first three lines of which are in the same meter and a fourth line, in a different (adonic) meter.
The first three lines look like this ( - = short syllable, ^ = long syllable, * = either, || = optional caesura):
- ^ - - - || ^ ^ - ^ - *
and the fourth line looks like this:
- ^ ^ - *
Example (in Latin, lines 3 and 4 of a stanza):
- ^ - - - || ^ ^ - ^ - ^
tintinant aures, gemina teguntur
- ^ ^ - ^
lumina nocte