"Underivative" is a word that means original or lacking influence from others. There are several synonyms for this word, including "independent," "uninfluenced," "unaffected," "autonomous," and "self-originated." Other possibilities include "unadulterated," "unbiased," "uncompromised," and "uninhibited." Each of these words carries a slightly different nuance, but they all reflect the idea of something that stands on its own, without external input. Whether describing a person's thinking, a work of art, or a scientific discovery, these synonyms all convey the importance of independence and originality, while also allowing for the possibility of collaboration and inspiration from others.