1876, "single card of a suit in a hand; a hand containing only one card of a suit," originally in whist, from single (adj.); compare simpleton, etc. Extended early 20c. to other instances of singularity.
Entries linking to singleton
single adj.
early 14c., "unmarried," from Old French sengle, sangle "alone, unaccompanied; simple, unadorned," from Latin singulus "one, one to each, individual, separate" (usually in plural singuli "one by one"), from PIE *semgolo‑, suffixed (diminutive?) form of root *sem- (1) "one; as one, together with."
The meaning "consisting of one unit, individual, unaccompanied by others" is from late 14c., often merely emphatic. The meaning "undivided" is from 1580s. Single-parent (adj.) is attested from 1966.
simpleton n.
"person of limited or feeble intelligence," 1640s, according to OED probably a jocular formation from simple and -ton, suffix extracted from surnames (and ultimately place-names). Compare skimmington, personification of an ill-used spouse, c. 1600; OED compares idleton from the English Dialect Dictionary. Century Dictionary sees it as a French diminutive of simplet, though no such diminutive had yet turned up. Also compare the -by terminations under rudesby.
single n.
c. 1400, "unmarried person," mid-15c., "a person alone, an individual," from single (adj.). Of single things from 1640s. From the broad sense of "that which is single" it was given various technical meanings from 16c.
The sports senses are attested from 1851 (cricket, "hit for which one run is scored") and 1858 (baseball, "one-base hit"). The meaning "one-dollar bill" is by 1936. The meaning "phonograph record with one song on each side" is from 1949. The sense of "unmarried swinger" is from 1964; singles bar, catering to the young and unmarried, is attested from 1969. An earlier modern word for "unmarried or unattached person" is singleton (1937).