Origin: ME o baft < OE on, on + bæftan < be, by + æftan, aft
See abaft in American Heritage Dictionary 4
Origin: Middle English on baft
Origin: : on, at; see on
Origin: + baft, to the rear (from Old English beǽftan, behind : be, by, at; see ambhi in Indo-European roots + ǽftan, behind; see apo- in Indo-European roots).