1540s, "quality of being real, objective reality," from French réalité and directly from Medieval Latin realitatem (nominative realitas), from Late Latin realis (see real (adj.)). Also compare realty, which was the older form of the word in the sense of "reality" (mid-15c.).
Meaning "real existence, what is real, the aggregate of all that is real" is from 1640s; that of "the real state (of something)" is from 1680s. Sometimes 17c.-18c. it also meant "sincerity." Reality-based is attested from 1960, in marriage counseling. Reality television is attested from 1991.
1660s, "real estate, real property," from earlier meaning "a real possession" (1540s), earlier still "reality" (mid-15c.), from Old French realite, realte, from Medieval Latin realitatem (nominative realitas), from Late Latin realis "actual" (see real (adj.)). The notion behind the word is the immobility, or the fixed, permanent nature of certain kinds of property, especially landed. Also compare reality.
1530s, "to have doubts (of the reality of), to suspect, to regard (the truth or reality of) with suspicion," from mis- (1) "badly, wrongly" + doubt (v.). Meaning "to fear or suspect (the existence of something evil) is from 1560s. Intransitive sense of "entertain doubt" is from 1630s. Related: Misdoubted; misdoubting. As a noun, "irresolution," 1590s.