Unacceptable means something that is not acceptable or not satisfactory. Its antonyms are words that signify the opposite or something that is acceptable. Some of the antonyms for unacceptable include acceptable, satisfactory, tolerable, delightful, pleasing, and welcome. Acceptable means that something is fitting or suitable, while satisfactory connotes a feeling of fulfillment or contentment. Tolerable implies that something is bearable or endurable. Delightful and pleasing imply that something evokes joy, pleasure, or happiness. Welcome suggests an enthusiastic reception of something. Overall, knowing the antonyms of unacceptable can help in expanding one's vocabulary and understanding the nuances of language.