An amphibrach is a metrical foot used in Latin and Greek prosody. It consists of a long syllable between two short syllables.
Amphibrachs are seldom used to construct an entire poem. They mainly occur as variants within, for instance, an anapaestic structure.
In English stress-based poetry, an amphibrach is a stressed syllable surrounded by two unstressed syllables. It is the main foot used in the construction of the limerick, e.g., "There was a | young lady | of Wantage"
The amphibrach is also often used in ballads and light verse, such as the hypermetrical lines of Sir John Betjeman's Meditation on the A40.
Some books by Dr. Seuss contain many lines written in amphibrachs, such as these from If I Ran the Circus:
Much of Leonard Cohen's song "Famous Blue Raincoat" is written in amphibrachs - e.g. the first verse (apart from the first foot of the third line, which is a spondee):