c. 1300, relacioun, "relationship, connection, correspondence;" late 14c. as "act of telling or relating in words," from Anglo-French relacioun, Old French relacion "report, connection" (14c.) and directly from Latin relationem (nominative relatio) "a bringing back, restoring; a report, proposition," from relatus (see relate).
The meaning "person related by blood or marriage" is attested from c. 1500. The phrase no relation "not in the same family," used in differentiating persons with the same surname, is attested by 1930.
1650s, "distinctive of either sex, of or pertaining to the fact of being male or female," from Late Latin sexualis "relating to sex," from Latin sexus "a sex, state of being either male or female, gender" (see sex (n.)).
The meaning "pertaining to copulation or generation" is from 1766, on the notion of "done by means of the two sexes;" hence also "pertaining to erotic appetites and their gratification" and "peculiar to or affecting the organs of sex, venereal" (1799). The phrase sexual intercourse is attested by 1771 (see intercourse), sexual orientation by 1967, sexual harassment by 1975. Sexual revolution is attested by 1962. Sexual politics is from 1970. Related: Sexually.
early 15c., "of or pertaining to sexual desire or intercourse," from Latin venereus, venerius "of Venus; of sexual love," from venus (genitive veneris) "sexual love, sexual desire" (from PIE root *wen- (1) "to desire, strive for"). Used of sexually transmitted diseases from 1650s. Related: Venereally.
late 14c., proporcioun, "due relation of one part to another," also "size, extent; comparative relation of one thing to another in size, degree, number, etc.," from Old French proporcion "measure, proportion" (13c.) and directly from Latin proportionem (nominative proportio) "comparative relation, analogy," from phrase pro portione "according to the relation" (of parts to each other), from pro "for" (see pro-) + ablative of *partio "division," related to pars "a part, piece, a share, a division" (from PIE root *pere- (2) "to grant, allot"). Also from late 14c. as "relation of body parts," hence "form, shape." Phrase out of proportion attested by 1670s.
My fortunes [are] as ill proportioned as your legs. [John Marston, "Antonio and Mellida," 1602]