Antonyms for the phrase "gave boost" include "diminished," "weakened," "lowered," "reduced," "inhibited," and "decreased." These words indicate a decrease or reduction in energy, power, or strength, rather than an increase. When someone or something gives a boost, they are providing a push or an increase in momentum, so the opposite would be a decrease or a slowing down. Antonyms can be useful for adding contrast to a piece of writing or for helping to clarify the exact meaning of a word or phrase.