"Un trustier" is a relatively uncommon word and is not commonly used in English language. However, if we were to try and find antonyms for the word, we could consider words such as trustworthy, reliable, dependable, honest, and credible. These words are typically used to describe people or things that can be relied upon and trusted. They convey an element of confidence and faith in the person or object being referred to. In contrast, "un trustier" would suggest exactly the opposite and imply that the person or object in question cannot be relied upon or trusted. Antonyms like trustworthy, therefore, help to create a positive impression and inspire confidence.