30 synonyms for insecure such as diffident, anxious, and apprehensive. Insecure is an adjective, and its antonyms are confident and assured.
Anxious, apprehensive, diffident, doubtful, fearful, hesitant, ill at ease, inhibited, introverted, lacking confidence, lacking self-confidence, meek, mousy, not self-assured, passive, retiring, self-conscious, self-doubting, self-effacing, shrinking, shy, timid, timorous, unassertive, uncertain, unconfident, unforthcoming, unsure, and worried.