Source : Webster's Revised Unabridged Dictionary (1913)

Abaft \A*baft"\ ([.a]*b[.a]ft"), prep. [Pref. a- on + OE. baft,
   baften, biaften, AS. be[ae]ftan; be by + [ae]ftan behind. See
   {After}, {Aft}, {By}.] (Naut.)
   Behind; toward the stern from; as, abaft the wheelhouse.

   {Abaft the beam}. See under {Beam}.

Abaft \A*baft"\, adv. (Naut.)
   Toward the stern; aft; as, to go abaft.

Source : WordNet®

abaft
     adv : at or near or toward the stern of a ship or tail of an
           airplane; "stow the luggage aft"; "ships with square
           sails sail fairly efficiently with the wind abaft";
           "the captain looked astern to see what the fuss was
           about" [syn: {aft}, {astern}] [ant: {fore}]