The Collaborative International Dictionary of English v.0.48:

Acockbill \A*cock"bill`\, adv. [Prefix a- + cock + bill: with
   bills cocked up.] (Naut.)
   (a) Hanging at the cathead, ready to let go, as an anchor.
   (b) Topped up; having one yardarm higher than the other.
       [1913 Webster]