environ vs cloister

environ is not a noun while cloister is a noun.

Word	Noun	Adjective	Verb	Adverb
environ	No	No	Yes	No
cloister	Yes	No	Yes	No

As verbs, cloister is a hyponym of environ; that is, cloister is a word with a more specific, narrower meaning than environ:

Other hyponyms of environ include fringe, gird, girdle, close in, enclose, inclose, shut in, hem in.

environ (noun)	cloister (noun)
	residence that is a place of religious seclusion (such as a monastery)
	a courtyard with covered walks (as in religious institutions)

environ (verb)	cloister (verb)
extend on all sides of simultaneously; encircle	seclude from the world in or as if in a cloister
	surround with a cloister
	surround with a cloister, as of a garden