foil

/ˈfȯi(-ə)l/

Middle English foilen "to trample, tread upon, mortify (the flesh), oppress," alteration of fullen "to full (cloth), trample down, oppress," perhaps by analogy with loanwords from French with palatal l that result in variants with -oi- and -u-, as coilen, cullen "to select for quality, pick out, "

verb

  1. to prevent from attaining an end : defeat

  2. to bring to naught : thwart

  3. trample

always able to foil her enemies

foiled the plot

frustrate thwart foil baffle balk mean to check or defeat another's plan or block achievement of a goal. frustrate implies making vain or ineffectual all efforts however vigorous or persistent. thwart suggests frustration or checking by crossing or opposing.

noun

  1. very thin sheet metal

  2. a thin piece of material (such as metal) put under an inferior or paste stone to add color or brilliance

  3. someone or something that serves as a contrast to another

aluminum foil

verb

  1. to back or cover with foil

  2. to enhance by contrast