Astern and In reverse

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

In reverse and astern are semantically related in rearwards topic. In some cases you can use "In reverse" instead the word "Astern" as an adverb or an adjective.

Astern and in reverse are semantically related in back topic. You can use "Astern" instead the phrase "In reverse" as an adverb or an adjective, if it concerns topics such as rearwards.