- foil (v.)
- c.1300, foilen "to spoil a trace or scent by running over it," from O.Fr. fouler "trample," from V.L. *fullare "to clean cloth" (by treading on it), from L. fullo "one who cleans cloth, fuller," of unknown origin. Sense of "frustrate the efforts of" first recorded 1664.
- foil (n.)
- "thin sheet of metal," late 14c., from O.Fr. fueille "leaf," from L. folia "leaves," pl. (mistaken for fem. sing.) of folium "leaf" (see folio). The sense of "one who enhances another by contrast" (1580s) is from the practice of backing a gem with metal foil to make it shine better. The meaning "light sword used in fencing" (1590s) could be from this sense, or from foil (v.). The modern sense of "metallic food wrap" is from 1946.