late 13c., from Latin brevis (adj.) "short, low, little, shallow," from PIE *mregh-wi-, from root *mregh-u- "short" (cognates: Greek brakhys "short," Old Church Slavonic bruzeja "shallow places, shoals," Gothic gamaurgjan "to shorten").

from Latin breve (genitive brevis), noun derivative of adjective brevis (see brief, adj.) which came to mean "letter, summary," specifically a letter of the pope (less ample and solemn than a bull), and thus came to mean "letter of authority," which yielded the modern, legal sense of "summary of the facts of a case" (1630s).

"to give instructions or information to," 1866; originally "to instruct by a brief" (1862), from brief, n.. Related: Briefed; briefing.