late 15c., "devoted to or relating to home life;" 1560s as "living with others," from Middle French social (14c.) and directly from Latin socialis "of companionship, of allies; united, living with others; of marriage, conjugal," from socius "companion, ally," probably originally "follower," from PIE *sokw-yo-, suffixed form of root *sekw- (1) "to follow," and thus related to sequi "to follow" (see sequel). Cf. Old English secg, Old Norse seggr "companion," which seem to have been formed on the same notion). Related: Socially.
Sense of "characterized by friendliness or geniality" is from 1660s. Meaning "living or liking to live with others; companionable, disposed to friendly intercourse" is from 1720s. Meaning "of or pertaining to society as a natural condition of human life" first attested 1695, in Locke. Sense of "pertaining to fashionable society" is from 1873.
Social climber is from 1893; social work is 1890; social worker 1904. Social drink(ing) first attested 1976. Social studies as an inclusive term for history, geography, economics, etc., is attested from 1916. Social security "system of state support for needy citizens" is attested from 1908. Social butterfly is from 1867, in figurative reference to "flitting."
Social contract (1849) ultimately is from Rousseau. Social Darwinism attested from 1887. Social engineering attested from 1899. Social science is from 1811. In late 19c. newspapers, social evil is "prostitution." Social justice is attested by 1718; social network by 1971; social networking by 1984.