set-back vs setoff

set-back and setoff both are nouns.

Word	Noun	Adjective	Verb	Adverb
set-back	Yes	No	No	No
setoff	Yes	No	No	No

As nouns, set-back and setoff are synonyms defined as:

set-back and setoff: structure where a wall or building narrows abruptly

Other synonyms of set-back include offset.

set-back (noun)	setoff (noun)
structure where a wall or building narrows abruptly	structure where a wall or building narrows abruptly