The chemical symbol of the metal didymium.[lowercase] An abbreviation of Latin dimidius, half.A prefix of Latin origin, the form of dis- before certain consonants: see dis-.A prefix of Greek origin, cognate with bi- (which see), and meaning ‘two-,’ ‘twofold,’ ‘double,’ as in dipterous, two-winged, diptych, a two-leaved tablet, diarchy, government by two, etc.A prefix of Greek origin, the form of dia- before a vowel.