When we say something is not fully formed, we mean that it is incomplete or inadequate. Synonyms for this phrase include immature, embryonic, nascent, incomplete, underdeveloped, and unfinished. These words describe something that has not yet reached its full potential or has not been fully realized. Other synonyms for not fully formed things might be inchoate, rudimentary, or incipient. These are words that describe things that are still being formed or are very early in the process of development. When searching for synonyms for not fully formed things, it is important to consider the context in which they are being used.