The term "am common" implies a state of being usual or widespread. Therefore, the antonym of this phrase would be uncommon or rare. Perhaps, we can also think of some other antonyms like peculiar, exclusive, unique, or unconventional, that all imply something that is different from what is ordinary or ordinary. These words can add a sense of uniqueness or individuality to a situation, object, or person. In contrast, being common can convey a sense of ordinariness, dissatisfaction, or mediocrity. Therefore, using antonyms of "am common" in our writing can help to convey a more nuanced meaning and tone.