common wildflower of Europe, growing in pastures and on mountainsides and cultivated in gardens, c. 1300, daiseie, from Old English dægesege, from dæges eage "day's eye;" see day (n.) + eye (n.). So called because the petals open at dawn and close at dusk. In Medieval Latin it was solis oculus "sun's eye." The use of dais eye for "the sun" is attested from early 15c.
Applied to similar plants in America, Australia, New Zealand. As a female proper name said to have been originally a pet form of Margaret (q.v.). Slang sense of "anything pretty, charming, or excellent" is by 1757.
Daisy-cutter first attested 1791, originally "a trotting horse," especially one that trots with low steps; later of cricket (1889) and baseball hits that skim along the ground. Daisy-chain is used in various figurative senses from 1856; the "group sex" sense is attested by 1941. Daisy-wheel for a removable printing unit in the form of a flat wheel is attested by 1974. Pushing up daisies "dead" is World War I soldier's slang from 1917 (see push (v.)), but variants with the same meaning go back to 1842.