to prevent the success of; frustrate; balk

Loyal troops foiled his attempt to overthrow the government.

to keep (a person) from succeeding in an enterprise, plan, etc.

Archaic . a defeat; check; repulse.

verb

abet , aid , assist , help

noun

antithesis , background , complement , counterblow , defense , guard , settingnotes:a fencing sword with a bowl-shaped guard and flexible blade is an pe ; the one with a circular guard is a foil

verb

baffle , balk , beat , bilk , bollix , buffalo , check , checkmate , counter , crab , cramp , crimp , curb , dash , defeat , disappoint , disconcert , ditch , dodge , duck , elude , faze , foul up * , frustrate , get around * , give the run-around , give the slip , hang up * , hinder , juke , nullify , outwit , prevent , rattle , restrain , run circles around , run rings around , shake , shake off , shuffle off , skip , stop , stymie , throw monkey wrench in , thwart , upset the apple cartnotes:a fencing sword with a bowl-shaped guard and flexible blade is an pe ; the one with a circular guard is a foil , aluminum , beguile , blade , blunt , boggle , circumvent , defile , disgrace , epee , evade , metal , obscure , overthrow , repulse , setback , stooge , sword , track , trail