Well, in fairness (strictly going by that article) it didn't have to mean "virgin" -- but it sometimes did:
"Almah (עלמה, plural: alamot עלמות) is a Hebrew word meaning a young woman of childbearing age who has not yet had a child, and who may be an unmarried virgin or a married young woman."
I'm not saying that Wikipedia gets the final say here, just pointing out what the quoted article says.
http://en.wikipedia.org/wiki/Almah