late 14c., "a cutting away, mutilation," also, from 16c., "circumcision," from Late Latin concisionem (nominative concisio) "a separation into divisions, a mutilation," literally "a cutting up," noun of action from past participle stem of Latin concidere "to cut off, cut up, cut through, cut to pieces," from assimilated form of com-, here probably an intensive prefix (see con-), + caedere "to cut" (from PIE root *kae-id- "to strike"). From 18c. it began to be used in the sense of conciseness (q.v.).
Beware of dogs, beware of evil workers, beware of the concision. For we are the circumcision, which worship God in the spirit, and rejoice in Christ Jesus, and have no confidence in the flesh. [Philippians iii.2-3]
In Philippians iii.2 it translates Greek katatome, a contemptuous substitution for the usual peritome "circumcision," in reference to the Judaizing teachers who taught that Christian converts must first be circumcised.