When you put the kibosh on something, you refuse to let it happen, or you bring it to an end. Your town may put the kibosh on dogs in the park if their owners don't clean up after them.
You'll almost always find the word kibosh in the phrase "put the kibosh on." Kids often feel like their teachers and parents are constantly putting the kibosh on their fun, and you may be disappointed when a rainy day puts the kibosh on your picnic plans. The origin of kibosh is unknown — though many people think it's Yiddish, the word's earliest use was probably in an Irish neighborhood in London in the early 1800s.