質問: The meanings and explanation of なんだか and なんとなく in Wikitionary: > > なんだか【何だか】明確な理由が無いさま。 > > > なんとなく【何と無く】明確な理由が無いさま。 > > > It seems that they have totally the same meanings. Is there a difference between the usage of these two adverbs?
回答: They mean very similar things. However, they are not totally interchangeable. The other definitions in the link you gave shows how they can be different. 1. なんとなく * 特に目的や動機などはなく、それといった理由もなく。 * 言動などに、はっきりとした理由・目的がないさま。なんとはなしに。 2. なんだか * 物事がはっきりしないさま。原因・理由などがよくわからないさま。 For なんとなく, there is no particular reason (or the reason is too petty to be considered). For なんだか, the speaker doesn't know the particular reason. This is why, the following sentences are correct: * その人なんとなく怖い。 * その人なんだか怖い。 But you can only use なんとなく in the following sentences: * Q. なんで行かないの? A. なんとなく。 * なんとなく理解できた。 And why, the following phrase sounds more romantic: * なんだか美しい。 than this: * なんとなく美しい。 This article summarizes it well, IMO.