slice (n.) Look up slice at Dictionary.com
c. 1300, "a fragment," from Old French escliz "splinter, fragment" (Modern French éclisse), a back-formation from esclicier "to splinter, shatter, smash," from Frankish *slitan "to split" or some other Germanic source (compare Old High German slihhan; see slit (v.)). Meaning "piece cut from something" emerged early 15c. Meaning "a slicing stroke" (in golf, tennis) is recorded from 1886. Slice of life (1895) translates French tranche de la vie, a term from French Naturalist literature.
slice (v.) Look up slice at Dictionary.com
late 15c., from Middle French esclicier, from Old French escliz (see slice (n.)). Golfing sense is from 1890. Related: Sliced; slicing. Sliced bread is attested from 1929 and was touted in advertisements; greatest thing since ... first attested 1969.
With the advent of ready sliced bread the bread board, the bread knife and the slicing machine pass out of the picture. Sliced bread is a radical departure in the baking industry and although the Weber Baking Company will continue to supply the trade with unsliced loaves, the company anticipates an unusual run on the ready sliced loaf. ["Western Hospital Review," Volume 14, 1929]



No matter how thick or how thin you slice it it's still baloney. [Carl Sandburg, "The People, Yes," 1936]