Not gullibly means being skeptical and not easily fooled. There are many synonyms for the word "not gullibly," including incredulous, wary, suspicious, doubtful, and cynical. Being incredulous means not being easily convinced, and being wary means being cautious and on guard. Suspicious means having doubts or suspicions about something or someone. Doubtful means not feeling confident about or unsure of something, and cynical means being distrustful of human nature and motives. All these synonyms emphasize the importance of being thoughtful and vigilant in one's interactions and decisions, rather than blindly accepting things at face value.