Is the 'virgin' in Isaiah 7:14 actually a virgin?

The Hebrew word in Isaiah 7:14 is עַלְמָה (ʿalmāh, H5959). It means a young woman of marriageable age — not a child, not an older woman, not a married woman. It is an age-class word, the way English speakers once used "maiden." It appears only seven times in the entire Hebrew Bible.

The technical Hebrew word for a virgin — a woman who has not had sex — is בְּתוּלָה (bĕtûlāh, H1330). That word appears fifty times in the canon. Isaiah did not use it here.

So does that mean the Septuagint's παρθένος (parthenos, G3933, "virgin") is wrong when it translates Isaiah 7:14?

No — and the reason why not is sitting in Genesis 24.

In Genesis 24:16, Rebekah is introduced with two descriptions stacked on each other: she is a bĕtûlāh (H1330, the technical virgin term) "whom no man had known." Then two verses later, at Genesis 24:43, the servant looking for her refers to her as an ʿalmāh (H5959) — the same word Isaiah uses for the woman in Isaiah 7:14. Same woman, same scene, two different words. The ʿalmāh is not a different woman. The ʿalmāh is a young unmarried woman who in that context is also a virgin.

This is how Hebrew age-class vocabulary works. ʿalmāh describes social stage and age — young, unmarried, in the household. It does not technically require virginity, but in the social context of the ancient Near East, a young unmarried woman of that stage was normally understood to be a virgin. The word does not exclude virginity; it simply does not define the category by it. Bĕtûlāh is the anatomical word. ʿalmāh is the social-stage word.

When the Septuagint translators — Jews who knew Hebrew, working in Alexandria around 200 BC — sat down to translate Isaiah 7:14, they chose παρθένος. That choice was deliberate. They understood ʿalmāh in its typical meaning: a young unmarried woman. And the standard Greek for that was παρθένος, which does carry the technical sense of sexual inexperience.

Matthew quotes the LXX when he writes:

"Behold, the virgin shall conceive and bear a son, and they shall call his name Immanuel." — Matthew 1:23 (citing Isaiah 7:14)

He quotes the Greek because Mary is exactly what Isaiah's word pointed toward: a young woman who had not known a man (Luke 1:34) and who nonetheless conceived. The LXX's παρθένος is not an overreach. It is the word that, when a virgin birth actually happened, turned out to be exactly right.

The sign Isaiah gave Ahaz was a young woman who would conceive and bear a son. That sign had a near-term fulfillment in Isaiah's own day — a child born to mark a timeline. But the sign also pointed past itself, the way many of Isaiah's prophecies do, toward a deeper fulfillment: not just a young woman, but a virgin; not just a child, but Immanuel, God-with-us. Matthew is not forcing Isaiah. He is showing that the word Isaiah chose — the age-class word that covered the social context of an unmarried young woman — turned out to describe precisely the one in whom the sign reached its fullest expression.

A note on the manuscript record. The claim is sometimes raised that the rabbis altered the Hebrew at Isaiah 7:14 — that the original read בְּתוּלָה ("virgin") and was changed to עַלְמָה ("young woman") after Christ. Three pre-Christ Hebrew witnesses refute this: 1QIsaᵃ (the Great Isaiah Scroll, c. 150–100 BC), 1QIsaᵇ, and 4Q65 (4QIsaˡ) all preserve הָעַלְמָה. There is no Hebrew manuscript tradition — pre-Christ or post-Christ — that reads בְּתוּלָה here. The MT is what Isaiah wrote; the LXX is what Matthew confirmed.

The full study Which Old Testament? walks through all seven occurrences of ʿalmāh and shows why the Septuagint's rendering reflects sound translation judgment, not theological wishful thinking.