The word "un-entertaining" means that something is not enjoyable or entertaining. The antonyms for the word "un-entertaining" are words that describe something that is engaging, interesting, or fun. Some of the antonyms of "un-entertaining" are entertaining, captivating, fascinating, interesting, engrossing, absorbing, amusing, enjoyable, and exciting. If something is described as entertaining, it means that it is enjoyable or interesting to watch, listen to, or participate in. Similarly, something that is captivating fascinates or holds one's attention, while something interesting is engaging and holds one's curiosity. Something that is engrossing absorbs one's attention, while something amusing is entertaining and enjoyable. Finally, something that is exciting is thrilling and stimulating.