What is "circum-"

Circum- \Cir"cum-\ [Akin to circle, circus.] A Latin preposition, used as a prefix in many English words, and signifying around or about.

word-forming element meaning "around, all around, on all sides," from Latin circum- a common element in word-formation, from adverb and preposition circum "around, round about," literally "in a circle," probably accusative form of circus "ring" (see circus). In French, the element became circon-; Kitchin points out that con for cum is common even in classical Latin.

pre. around