The term 'keep from happening' can be defined by the crossword solutions of BLOCK, PREVENT, AVERT, AVOID, FOIL, DETER, and THWART. BLOCK is an action that stops something from passing or entering, while PREVENT is to stop something from happening. AVERT is to turn away or PREVENT something from happening, and AVOID is to keep away from or stay clear of something. FOIL is to PREVENT something from succeeding, DETER is to discourage someone from doing something, and THWART is to PREVENT someone from achieving a goal. All of these words are related to the idea of keeping something from happening.