A set pattern of stressed (S) and unstressed (US) sounds (syllables) used in verse.
In English, most words are in one of these five groupings:
Iambic foot or iamb: An US (short) syllable followed by a S (long). {Today, about, repeat}
Trochaic foot or trochee: S, followed by a US. {Meter, pleasant, daily}
Anapestic foot or anapest: 2 US followed by 1 S. {Intercede, for the nonce}
Dactylic foot, or dactyl:1 S, followed by 2 US. {Silvery, national, penitent}
Spondiac foot or spondee: 2 S {Thirteen. deadbeat}
Other feet are Amphibrach, Amphimacer, Antibacchius, Bacchic, and Pyrrhic.
Trochee / trips from / long to / short;
From long to long in solemn sort
Slow Spon/dee stalks; / strong foot! / yet ill / able
Ever to / come up with / Dactyl tri/syllable.
Iam/bic march / from short / to long;
With a leap / and a bound / the swift An/apaests throng.
--Coleridge