The word "nullipotent" is a relatively rare term that refers to a lack of power or inability to act or affect something. Synonyms for this word include impotent, powerless, weak, ineffective, and ineffectual. Other similar terms that may be used in place of "nullipotent" include powerless, helpless, feeble, inept, and inadequate. While these words all convey a sense of weakness or inability, they may have slightly different nuances and connotations. Ultimately, the choice of synonym will depend on the context and specific meaning intended, but these words can all help to convey the idea of a lack of power or ability.