Middle English sellen, from Old English sellan "to give (something to someone), furnish, supply, lend; surrender, give up; deliver to; promise," from Proto-Germanic *saljanan "offer up, deliver" (source also of Old Norse selja "to hand over, deliver, sell;" Old Frisian sella, Old High German sellen "to give, hand over, sell;" Gothic saljan "to offer a sacrifice"), ultimately from PIE root *sel- (3) "to take, grasp."
Meaning "to give up for money, accept a price or reward for" had emerged by late Old English, but in Chaucer selle still can mean "to give." Students of Old English learn early that the word they encounter that looks like sell usually means "give." An Old English word for "to sell" was bebycgan, from bycgan "to buy."
The meaning "betray for gain" is from c. 1200. Slang meaning "to swindle" is from 1590s. To sell off "dispose of by sale, sell all of" is by 1700. To sell one's soul "make a contract with the devil," often figurative, is from c. 1570. Sell-by in reference to dates stamped on perishable packaged foods is from 1972. To sell like hot cakes is from 1839. To sell (someone) down the river figuratively is by 1927, probably from or with recollection of slavery days, on notion of sale from the Upper South to the cotton plantations of the Deep South (attested in this literal sense since 1851).
c. 1400, "devoted to or relating to home life;" 1560s as "living with others," from 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." Compare 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 1886. Social drinking first attested 1807. 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 1907 (the Social Security Act was passed by U.S. Congress in 1935). Social butterfly is from 1867, in figurative reference to "flitting."
Social contract (1763) is from translations of Rousseau. Social Darwinism attested from 1887. Social engineering attested from 1899. Social science is from 1785. In late 19c. newspapers, social evil is "prostitution." Social network is attested by 1971; social networking by 1984; social media by 2008. Social justice is attested by 1718.
I must introduce a parenthetical protest against the abuse of the current term 'social justice'. From meaning 'justice in relations between groups or classes' it may slip into meaning a particular assumption as to what these relations should be; and a course of action might be supported because it represented the aim of 'social justice', which from the point of view of 'justice' was not just. The term 'social justice' is in danger of losing its rational content—which would be replaced by a powerful emotional charge. I believe that I have used the term myself: it should never be employed unless the user is prepared to define clearly what social justice means to him, and why he thinks it just. [T.S. Eliot, footnote in "Notes Towards the Definition of Culture," 1948]