fancyyoudaoicibaDictYouDict[fancy 词源字典]
fancy: [15] Ultimately, fancy is the same word as fantasy [15], from which it emerged by a process of contraction and gradually became differentiated in meaning. Both go back originally to the Greek verb phaínein ‘show’ (source also of English diaphanous and phenomenon). From it was derived phantázein ‘make visible’, which produced the noun phantasíā ‘appearance, perception, imagination’ and its associated adjective phantastikós ‘able to make visible’ (and also incidentally phántasma, from which English gets phantasm and phantom).

The noun passed into English via Latin phantasia and Old French fantasie, bringing with it the original Greek senses and also some others which it had picked up on the way, including ‘caprice’. The semantic split between fantasy, which has basically taken the road of ‘imagination’, and fancy, which has tended more to ‘capricious preference’, was more or less complete by about 1600.

The quasi- Greek spelling phantasy was introduced in the 16th century, and has persisted for the noun, although the contemporary phantastic for the adjective has now died out. The Italian form fantasia was borrowed in the 18th century for a fanciful musical composition. (Fancy and fantasy have no etymological connection with the superficially similar fanatic, incidentally, which comes ultimately from Latin fānum ‘temple’.)
=> diaphanous, fantasy, pant, phantom[fancy etymology, fancy origin, 英语词源]
fancy (n.)youdaoicibaDictYouDict
mid-15c., fantsy "inclination, liking," contraction of fantasy. It took the older and longer word's sense of "inclination, whim, desire." Meaning "the productive imagination" is from 1580s. That of "a fanciful image or conception" is from 1660s. Meaning "fans of an amusement or sport, collectively" is attested by 1735, especially (though not originally) of the prize ring. The adjective is recorded from 1751 in the sense "fine, elegant, ornamental" (opposed to plain); later as "involving fancy, of a fanciful nature" (1800). Fancy man attested by 1811.
fancy (v.)youdaoicibaDictYouDict
"take a liking to," 1540s, a contraction of fantasien "to fantasize (about)," from fantasy (n.). Meaning "imagine" is from 1550s. Related: Fancied; fancies; fancying. Colloquial use in fancy that, etc. is recorded by 1813.