Overweeningly is an adverb that means excessively or arrogantly. Some synonyms that can be used instead of overweeningly include: haughtily, pompously, pretentiously, superciliously, conceitedly, egotistically, self-importantly, snobbishly, narcissistically, and cockily. These words depict a sense of overconfidence and superiority in oneself, which can be perceived as negative traits. It is essential to be mindful of using such words in a context that demands it. However, it's important to note that some of these synonyms hold unique connotations and should be carefully chosen based on their aptness in a particular sentence or context.