verb
foils; foiled; foiling
[+ obj] to prevent (someone) from doing something or achieving a goal :defeat
to prevent (something) from happening or being successful
noun
plural foils
[noncount] :a very thin and light sheet of metal
[count] :someone or something that is different from another person or thing in a useful or appealing way - usually + for or to
[count] :a sword that has a light, thin blade and that is used in the sport of fencing