As nouns the difference between environs and circumjacency
is that environs is the surroundings; the environment while circumjacency is an area circumjacent to another; surroundings, environs.
As a verb environs
is (environ).
environs
English
Verb
(head)
(environ)
----
circumjacency
English
Noun
An area circumjacent to another; surroundings, environs.