Stealthful is an adjective used to describe something that is done in a secretive or sneaky manner. Synonyms for this word include covert, furtive, surreptitious, and undercover. Covert suggests a hidden or disguised nature, while furtive implies a cautious or nervous secretive quality. Surreptitious signifies a more deliberate and intentional secrecy, and undercover is typically associated with disguising one's identity to gather information. Other synonyms for stealthful include sly, cunning, and devious, suggesting a manipulative or deceitful quality. Ultimately, whether you're trying to describe a spy sneaking through the shadows or a sneaky child trying to steal a cookie, there are plenty of synonyms to choose from to capture the stealthful act.