In Greek and Latin poetry, a choriamb /ˈkɔːriˌæmb/ is a metron (prosodic foot) consisting of four syllables in the pattern long-short-short-long (— ‿ ‿ —), that is, a trochee alternating with an iamb. Choriambs are one of the two basic metra that do not occur in spoken verse, as distinguished from true lyric or sung verse. The choriamb is sometimes regarded as the "nucleus" of Aeolic verse, because the pattern long-short-short-long pattern occurs, but to label this a "choriamb" is potentially misleading.
In the prosody of English and other modern European languages, "choriamb" is sometimes used to describe four-syllable sequence of the pattern stressed-unstressed-unstressed-stressed (again, a trochee followed by an iamb): for example, "over the hill", "under the bridge", and "what a mistake!".
In English, the choriamb is often found in the first four syllables of iambic pentameter verses, as here in Keats' To Autumn:
tomorrow will be glommy with a chance of morning frogs but this just happened to me while i was sawin' logs i seen a striptease torture and blackbirds flyin' backwards and a pagan rout in a hellhole in a bed full o' crackers it was a wet nightmare.... there was a pin up girl painted on the wall of a cave a wolf whistle and a leather girl and a slave i got the mascara whiplash from a shockwave o'showgals stripped gears an' firls an' reemed an' stroked valves it was a wet nightmare she-wolves in six-packs put on warpaint in an earthquake i drank booze from their shoes with no pants or brakes a load o'girl in arms and a bit in my teeth panties on my head.....corkscrew heels on my feet it was a wet nightmare