Fearful or wary of being supplanted; apprehensive of losing affection or position. Resentful or bitter in rivalry; envious: jealous of the success of others. Inclined to suspect rivalry. Having to do with or arising from feelings of envy, apprehension, or bitterness: jealous thoughts. Vigilant in guarding something: We are jealous of our good name. Intolerant of disloyalty or infidelity; autocratic: a jealous God.