The word "un-handiness" refers to a lack of dexterity, clumsiness, or difficulty in performing tasks. Antonyms for this word could include adjectives such as nimble, deft, graceful, skilled, or agile, which describe someone who is physically coordinated and adept at performing tasks. Other antonyms could be words like usefulness, convenience or adaptability, which describe objects, tools, or spaces that are well-suited for their intended purpose and make tasks easier to perform. Additionally, words like efficiency, speed, and fluidity could be considered antonyms since they describe a smooth and effortless performance of tasks.