Entry 1 sense Webster, 1913 Prochronism · Pro·chro·nism · IPA /ˈpɹoʊkɹənɪz(ə)m/ 01 n. The dating of an event before the time it happened; an antedating; -- opposed to metachronism. 1. The dating of an event before the time it happened; an antedating; -- opposed to metachronism.