expression, adverb
visibly; noticeably; remarkably
Describes a change or difference that is clearly observable, often with a nuance of being striking or significant.
彼は目に見えて痩せた。
He has visibly lost weight.
練習の成果が目に見えて現れた。
The results of practice became noticeably apparent.
明らかに means 'clearly' or 'obviously' in a logical sense, while 目に見えて emphasizes a visible, tangible change.
はっきり is a general adverb for 'clearly' (can be visual, auditory, or mental), whereas 目に見えて specifically refers to something that can be seen or observed.
From 目 (eye) + に + 見えて (te-form of 見える, to be visible). Literally 'appearing to the eye'.