[all-] or allo- comb form [Gk, fr. allos other--more at else] 1: other: different: atypical "allogamous" "allotropy"
2. allo-: isomeric form or variety of (a specified chemical compound) "allopurinol" 3 allo-: being one of a group whose members together constitute a structural unit esp. of a language "allophone"