about turn vs reversion

about turn and reversion both are nouns.

Word	Noun	Adjective	Verb	Adverb
about turn	Yes	No	No	No
reversion	Yes	No	No	No

As nouns, reversion is a hypernym of about turn; that is, reversion is a word with a broader meaning than about turn:

Other hypernyms of about turn include reversal, reverse, turnabout, turnaround.

about turn (noun)	reversion (noun)
act of pivoting 180 degrees, especially in a military formation	a failure to maintain a higher state
	turning in the opposite direction
	returning to a former state
	(genetics) a return to a normal phenotype (usually resulting from a second mutation)
	a reappearance of an earlier characteristic
	(law) an interest in an estate that reverts to the grantor (or his heirs) at the end of some period (e.g., the death of the grantee)