The word "redoubtable" refers to someone or something that is formidable or impressive, often in terms of power, skills, or reputation. Antonyms for "redoubtable" include insignificant, unimpressive, ordinary, powerless, and weak. These words describe people or things that lack the qualities that make them formidable or impressive. "Insignificant" describes someone or something that is not important or influential. "Unimpressive" describes someone or something that fails to impress or make an impact. "Ordinary" describes someone or something that is unremarkable or average. Finally, "powerless" and "weak" describe people or things that lack the ability to achieve their objectives or protect themselves from harm.