1Somewhat; a little; somehow — used to express a vague feeling or impression without a clear reason. Very common in conversation; usually written in kana.
なんだか今日は気分がいい。
Somehow I feel good today.
部屋がなんだか寒いと思ったら、窓が開いていた。
The room felt kind of cold, and it turned out a window was open.
その映画、なんだか最後が物足りなかった。
That movie's ending felt somewhat unsatisfying, somehow.
彼の態度がなんだか気になる。
His attitude bothers me for some reason.