TO FOIL - [verb] to prevent somebody from doing something
Examples of use
Fortunately, the burglary was foiled by the police in time.
We need to foil him, or he will marry the wrong woman, making the biggest mistake of his life.
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English speaking practise
Remember that if you don't use that word in English conversations or writing you'll forget it in a short time. So the best thing you can do to learn this word is just trying to use it in speaking or writing. Remember also that practise is the key to fluent english speaking.
You can always find a partner, who would also like to improve his/her