“foolish.” The Greek word is mōros (#3474 μωρός), which means “foolish,” or “stupid,” but is also used for godless or impious. This is a good example of a place when the full meaning of the Greek word cannot be brought into the English translation unless it is expanded. The virgins were not just “foolish,” they were almost certainly “godless” as well, which is why they did not make the effort to be prepared for the bridegroom. The parable is about being ready for the coming of the Lord, and while those who do not prepare are indeed foolish, they are also godless.
“sensible.” The Greek word is phronimos (#5429 φρόνιμος), and it refers to using one thought, being prudent, thoughtful, sensible, intelligent, wise, in contrast to the word sophos,(#4680 σοφός) the more common Greek word that more commonly means “wise.”