late 14c., "to encompass; confine, restrain, mark out bounds or limits for," from Latin circumscribere "to make a circle around, encircle, draw a line around; limit, restrain, confine, set the boundaries of," from circum "around, round about" (see circum-) + scribere "to write" (from PIE root *skribh- "to cut"). Related: Circumscribed; circumscribing.

1530s, "the laying down of limits," from Latin circumscriptionem (nominative circumscriptio) "an encircling; fact of being held to set limits," noun of action from past participle stem of circumscribere "make a circle around; restrain, confine, set the boundaries of" (see circumscribe).

Earliest use is figurative, of meanings. Meaning "fact or quality of being circumscribed" is from 1540s; that of "act of bounding, settling, or determining" is from c. 1600. Sense of "a circular inscription" (on a coin, seal, etc.) is from 1560s.

also *ker-, Proto-Indo-European root meaning "to turn, bend."

It forms all or part of: arrange; circa; circadian; circle; circuit; circum-; circumcision; circumflex; circumnavigate; circumscribe; circumspect; circumstance; circus; cirque; corona; crepe; crest; crinoline; crisp; crown;  curb; curvature; curve; derange;  flounce (n.) "deep ruffle on the skirt of a dress;" krone; ring (n.1) "circular band;" ranch; range; ranger; rank (n.) "row, line series;" research; recherche; ridge; rink; rucksack; search; shrink.

It is the hypothetical source of/evidence for its existence is provided by: Latin curvus "bent, curved," crispus "curly;" Old Church Slavonic kragu "circle;" perhaps Greek kirkos "ring," koronos "curved;" Old English hring "ring, small circlet."