Jeopardize means to put at risk or pose a threat. Jeopardize your career by posting silly pictures of yourself on Facebook. Jeopardize your friendships by posting silly pictures of your friends on Facebook.
Jeopardize stems from the Old French jeu parti, which literally translates to a game with divided, or even, chances. An even chance of winning hardly seems a risky endeavor, but maybe our forefathers weren't big risk-takers. Whatever the reason, jeopardize has come to mean the act of putting yourself or something at risk, through circumstance or behavior. Think of double-jeopardy on the gameshow "Jeopardy" and you'll better understand what it means to jeopardize your savings.