Having no head. / (zoology, applied to bivalve mollusks) Without a distinct head. / (botany) Having the style spring from the base, instead of from the apex, as is the case in certain ovaries

Without a head. / Leaderlessly; without a leader. / (document studies) Without its beginning.

Without a head. / (medicine, of a headache, dated) Characterized by a migraine aura without pain. / Without a leader.