Lewis & Short

† ăcĕphălus, i, adj., = ἀκέφαλος.

  1. I. Without head, without chief or leader.
    Subst.: Ăcĕphăli, a sect of heretics, Isid. Or. 8, 5, 66; cf. 5, 39, 39 sq.
  2. II. In prosody, of a hexameter which begins with a short syllable (e. g. ἐπειδή), Vel. Long. p. 2219 P.