Over-confidence is a state of mind that occurs when an individual has an excessive amount of self-assurance or belief in their abilities. When one is over-confident, they may feel that they already know everything and become less receptive to new information or ideas. There are several synonyms for over-confidence that can be used to describe this state of mind, such as arrogance, conceit, hubris, haughtiness, superiority, presumptuousness, and overweening. Each of these terms reflects the excessive belief in oneself that can lead to irrational beliefs and behavior. While some level of self-belief can be a positive attribute, it is important to avoid the pitfalls of over-confidence to remain balanced, grounded, and receptive.