Meaning

verb extend on all sides of simultaneously; encircle

originFrom Middle English enviroun (“round about in a circle or ring; all around”) [and other forms], from Anglo-Norman enviroun, environ [and other forms], and Middle French enviroun, environ [and other forms], from Old French environ (“around, surrounding; about, approximately, roughly”) (modern French environ), from en- (prefix meaning ‘in; into’) + viron (“circuit; circumference, compass; country…

Etymology from Wiktionary, CC BY-SA 3.0