kind of cotton cloth, originally usually yellow, 1755, from Nanking, China, where it originally was made. Also "trousers or breeches made of nankeen" (1806).
"loose trousers of a strong material worn by cowboys, etc.," 1782, from over (adv.) + all. Specific sense "loose fitting canvas trousers with a bib and strap top" (originally worn by workmen over other clothes to protect them from wet, dirt, etc.) is attested by 1897. Compare French surtout "overcoat," literally "an over all," from sur- "over" + tout "all."
also nicky tam, "garter worn over trousers," 1911, Scottish, from a shortened, colloquial form of knickers + Scottish & northern English dialect taum, from Old Norse taumr "cord, rein, line," cognate with Old English team, the root sense of which appears to be "that which draws" (see team (n.)). Originally a string tied by Scottish farmers around rolled-up trousers to keep the legs of them out of the dirt.