(n.) A foot of three syllables, the middle one long, the first and last short (~ -- ~); as, h/b/r/. In modern prosody the accented syllable takes the place of the long and the unaccented of the short; as, pro-phet#ic.
AMPHIBRACH
Meaning of AMPHIBRACH in English
Webster's English dictionary. Английский словарь Webster. 2012