Elem (עֶלֶם) refers to a young man or youth — one in the season of vitality and growth. It appears only about 4 times in the Old Testament. The feminine form almah (H5959) is much more famous — appearing in Isaiah 7:14 ('the virgin/young woman shall conceive'). Understanding elem helps clarify the semantic range of the almah debate.
The significance of elem lies primarily in its connection to the root family. The famous almah of Isaiah 7:14 (used in Matthew 1:23 for the virgin birth) comes from this same root — a young woman of marriageable age, typically unmarried. The Greek parthenos (virgin) in Matthew captures the full meaning. Elem itself appears in 1 Samuel 17:56 (asking whose son the young David is) and in 1 Samuel 20:22 (the lad/boy in Jonathan's archery signal to David). Youth in Scripture is not dismissed but deployed — David the young shepherd becomes the king; Timothy is told not to let anyone look down on him because of his youth.