Unfoundedly is an adverb that means without any supporting evidence or justification. Synonyms for this word include baselessly, groundlessly, unjustifiably, unreasonably, and without cause. These words all share a similar meaning of lacking solid reasoning or support. Other synonyms that could be used in context include speciously, falsely, and wrongly. It's important to choose the appropriate synonym based on the context in which it's being used, as some words may convey a stronger sense of disbelief or suspicion. When making an argument or presenting a case, it's crucial to ensure that all statements are backed up with evidence to avoid being accused of making unfounded claims.