Aft and Back of

Aft adverb - Near, toward, or in the stern of a ship or the tail of an aircraft.

Back of and aft are semantically related In some cases you can use "Back of" instead the word "Aft" as an adjective or an adverb.

Back of preposition - At, to, or toward the rear of.

Aft and back of are semantically related in end topic. You can use "Aft" instead the phrase "Back of" as an adjective or an adverb, if it concerns topics such as back.