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"
Aft of any particular point on the vessel; e g , abaft the mast — behind the mast
[ &-'baft ] (preposition.) 1594. From a- (“on”) + Middle English baft, baften, biaften, Old English beæftan; be (“by”) (modern English by) + æftan (“behind”) (modern English after). See also aft.