early 14c., "actually existing, true;" mid-15c., "relating to things" (especially property), from Old French reel "real, actual," from Late Latin realis "actual," in Medieval Latin "belonging to the thing itself," from Latin res "matter, thing," of uncertain origin. Meaning "genuine" is recorded from 1550s; sense of "unaffected, no-nonsense" is from 1847.
Real estate is first recorded 1660s and retains the oldest English sense of the word. Noun phrase real time is early 19c. as a term in logic and philosophy, 1953 as an adjectival phrase; get real, usually an interjection, was U.S. college slang in 1960s, reached wide popularity c.1987.