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.

Source: Webster's Revised Unabridged Dictionary (1913)
 

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

Source: Webster's Revised Unabridged Dictionary (1913)