Unappreciably refers to something that cannot be perceived or detected. The antonyms of unappreciably are detectable, noticeable, significant, appreciable, considerable, and substantial. When something is detectable or noticeable, it means that it can be easily observed, felt, or experienced. Similarly, if something is significant, it means that it has some importance, value, or impact. Appreciable, considerable, and substantial all refer to the degree to which something can be measured or evaluated. Therefore, using these antonyms will help convey the opposite meaning of unappreciably and make writing more nuanced and clear.