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 "property, goods, matter, thing, affair," which de Vaan traces to a PIE *Hreh-i- "wealth, goods," source also of Sanskrit rayim, rayah "property, goods," Avestan raii-i- "wealth."
The meaning "genuine" is recorded from 1550s; the sense of "unaffected, no-nonsense" is from 1847.
Generally, by the time you are Real, most of your hair has been loved off, and your eyes drop out and you get loose in the joints and very shabby. But these things don't matter at all, because once you are Real you can't be ugly, except to people who don't understand. [Margery Williams, "The Velveteen Rabbit"]
Real estate, the exact term, is recorded from 1660s, but in Middle English real was used in law in reference to immovable property, paired with, and distinguished from, personal. 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.