Thwarter is a word that means to obstruct or prevent something from happening. There are several synonyms for thwarter, including frustrate, impede, foil, block, hinder, or stymie. Frustrate means to make someone feel annoyed or disappointed, whereas impede means to slow down or stop the progress of something. Foil means to prevent a plan from succeeding, and block refers to stopping someone from achieving their goals. Hinder means to create difficulties that prevent someone from doing something, and stymie means to obstruct or block someone's progress. All these words have a similar meaning to thwarter and can be used interchangeably in different contexts where it's necessary to express a sense of obstruction or prevention.