왠지 + feeling: 왠지 기분이 좋아요, 왠지 불안해요
somehow, for some reason
Example
오늘은 왠지 좋은 일이 생길 것 같아요.
Somehow I feel like something good will happen today.
Word parts
Contraction of 왜인지 'why it is (I don't know)'.
Good to know
Classic spelling trap: 왠지 (from 왜) vs. 웬 'what kind of', as in 웬일이에요?