The phrase "give a boost" is often associated with providing support, encouragement or assistance to someone or something. However, there are several antonyms to this phrase which connote the opposite meanings. Some of the antonyms to "give a boost" are "deter", "hinder", "discourage", "impede" and "obstruct". These words suggest actions that block or slow down progress, decrease motivation or discourage efforts. For instance, telling someone they can't do something, or putting obstacles in their way, will deter or hinder them from achieving their goals. While giving a boost can lead to positive outcomes, the use of antonyms can have negative impacts. Therefore, it's important to choose words carefully when trying to communicate effectively.