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1520s, "taste, flavor," alteration of reles "scent, taste, aftertaste," (c.1300), from Old French relais, reles, "something remaining, that which is left behind," from relaisser "to leave behind" (see release (v.)). Meaning "enjoyment of the taste or flavor of something" is attested from 1640s. Sense of "condiment, that which imparts flavor" is first recorded 1797. The stuff you put on hot dogs is a sweet green pickle relish.
1560s "give flavor to" (implied in relished), from relish (n.). The transferred sense of "to enjoy, take pleasure in" is from 1590s. Related: Relishing.
vegetable side dish that is eaten in small quantities with a blander main dish to pique the appetite by its contrasting texture and spicy or piquant taste. Relishes are frequently finely cut vegetables or fruit in sour, sweet-sour, or spicy sauce. The Indonesian and Malaysian sambal, Indian chutney, achar, and raita, and Korean kimchi are relishes that accompany virtually every meal in their respective cuisines. Lombardy in Italy specializes in mostarda di frutta, a melange of fruits preserved in a sweet syrup, sharp with mustard. In the Pennsylvania Dutch (see Pennsylvania German) cuisine of the United States, "seven sweets and seven sours" traditionally were served, among them many that are favourites throughout the country: pickled cucumbers, onions, beets, crabapples, watermelon rind, and mixtures of chopped vegetables such as piccalilli and chow chow.