This is right from the “Hell” link above:
The Latin infernus (inferum, inferi), the Greek Hades, and the Hebrew sheol correspond to the word hell. Infernus is derived from the root in; hence it designates hell as a place within and below the earth. Haides, formed from the root fid, to see, and a privative, denotes an invisible, hidden, and dark place; thus it is similar to the term hell. The derivation of sheol is doubtful. It is generally supposed to come from the Hebrew root meaning, “to be sunk in, to be hollow”; accordingly it denotes a cave or a place under the earth. In the Old Testament (Sept. hades; Vulg. infernus) sheol is used quite in general to designate the kingdom of the dead, of the good (Gen., xxxvii, 35) **as well as of the bad ** (Num., xvi, 30); it means hell in the strict sense of the term, as well as the limbo of the Fathers. But, as the limbo of the Fathers ended at the time of Christ’s Ascension, hades (Vulg. infernus) in the New Testament always designates the hell of the damned.