Source : Webster's Revised Unabridged Dictionary (1913)

Acephalous \A*ceph"a*lous\, a. [See {Acephal}.]
   1. Headless.

   2. (Zo["o]l.) Without a distinct head; -- a term applied to
      bivalve mollusks.

   3. (Bot.) Having the style spring from the base, instead of
      from the apex, as is the case in certain ovaries.

   4. Without a leader or chief.

   5. Wanting the beginning.

            A false or acephalous structure of sentence. --De
                                                  Quincey.

   6. (Pros.) Deficient and the beginning, as a line of poetry.
      --Brande.

Source : WordNet®

acephalous
     adj : lacking a head or a clearly defined head; "acephalous worms"