Adam Clarke on Genesis 24:43

When the virgin - העלמה haalmah, from עלם alam, to hide, cover, or conceal; a pure virgin, a woman not uncovered, and in this respect still concealed from man. The same as בתולה bethulah, Gen 24:16, which, from the explanation there given, incontestably means a virgin in the proper sense of the word - a young woman, not that is covered or kept at home, the common gloss, but who was not uncovered in the delicate sense in which the Scripture uses this word. See this interpretation vindicated on Isa 7:14 (note).