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.

FOIL definition: to prevent the success of; frustrate; balk. See examples of foil used in a sentence.

FOIL definition: 1. a very thin sheet of metal, especially used to wrap food in to keep it fresh: 2. a piece of a…. Learn more.

Look up foil in Wiktionary, the free dictionary.

One that stands in contrast to and emphasizes the distinctive characteristics of another: "I am resolved my husband shall not be a rival, but a foil to me" (Charlotte Brontë).

Dec 24, 2025 · foil (countable and uncountable, plural foils) A very thin sheet of metal or plastic. (chiefly uncountable) Thin aluminium / aluminum (or, formerly, tin) used for wrapping food. A thin layer of …

FOIL meaning: 1 : to prevent (someone) from doing something or achieving a goal defeat often used as (be) foiled; 2 : to prevent (something) from happening or being successful