The term "be illegitimate" refers to the status of something or someone being invalid or illegal. There are several synonyms for this word including unlawful, illicit, unauthorized, illegitimate, and invalid. Each of these words shares the connotation of something being improper or outside the scope of what is allowed. Other synonyms for "be illegitimate" include fraudulent, fake, spurious, and bogus. Regardless of the specific word used, all these synonyms convey the idea that something is not in accordance with the law or established norms. It is important to understand these synonyms when discussing legal or moral issues related to legitimacy.