Behold, the virgin (?) shall conceive? Yes. Virgin.

 The questions are flying now about Isaiah 7:14, and the translation of the verse.  

The Hebrew word in question is

הָֽעַלְמָה֙

ha-almah

It appears 9 times in the Tanakh (Old Testament).  Twice it is used as a name, and therefore not translated those times (just like the word "Moses" means "drawn out of the water," but we just write "Moses" instead of translating it).    

It means "Young woman of marriageable age."  

The Lexham Research Lexicon of the Hebrew Bible defines it this way:

Noun Usage

    1.      young woman — a young woman, possibly of marriageable age, whether married or not. 

Brown-Driver-Briggs defines it this way:

עַלְמָה n.f. young woman (ripe sexually; maid or newly married); עַל־עֲלָמוֹת to (the voice of) young women, either lit., or of soprano or falsetto of boys.

And HALOT defines it this way:

עַלְמָה: pl. עֲלָמוֹת: girl (of marriageable age), young woman (until the birth of first child) Gn 24:43; Is 7:14; unexplained term in performance Ps 46:1; 1 C 15:20.

It appears in:

Genesis 24:43.  

JPS Translation: maiden

ESV Translation: virgin

Exodus 2:8

JPS Translation: maiden

ESV Translation: girl

Isaiah 7:14

JPS Translation: young woman

ESV Translation: virgin

Psalms 68:26

JPS Translation: damsels

ESV Translation: virgins

Proverbs 30:19

JPS Translation: young woman

ESV Translation: virgin

Song 1:3

JPS Translation: maidens

ESV Translation: virgins

Song 6:8

JPS Translation: maidens

ESV Translation: virgins

Now, given the JPS translation of "maiden" in 4 of these 7 cases, there is a very solid understanding of the word to mean a woman who has not yet known a man.  While it is certainly possible that Almah means a young woman newly married who has not yet conceived but is no longer a virgin, looking at the context of Isaiah 7:14 rules that out in this case.

How?

Isaiah 7:14 (ESV) 

Therefore the Lord himself will give you a sign. Behold, the virgin shall conceive and bear a son, and shall call his name Immanuel.

Isaiah 7:14 (JPS)

Therefore the Lord Himself shall give you a sign: behold, the young woman shall conceive, and bear a son, and shall call his name Immanuel.

Which one of these is a miracle?  Which of these two translations is a "sign" from the Lord?  That a young woman has a baby?  Or that a virgin has a baby?

My wife was 19 when she had her first baby... nobody thought it was miraculous.  Certainly it was a special thing, but there were dozens of other similarly aged women all on the same floor of the hospital doing exactly the same thing at exactly the same time... not a "sign" from the Lord.

But if a Virgin conceives and bears a son, that's different.  And before you object, no, a virgin cannot conceive. She ceases to be a virgin when she conceives.  But if she is a virgin when she bears the son, as Isaiah tells us, then that's something different.

Let's look also, for a moment, at Deuteronomy 22:20-21 (ESV):

 20 But if the thing is true, that evidence of virginity was not found in the young woman, 21 then they shall bring out the young woman to the door of her father’s house, and the men of her city shall stone her to death with stones, because she has done an outrageous thing in Israel by whoring in her father’s house. So you shall purge the evil from your midst. 

Please feel free to check the context of this for yourself and be sure I'm not misrepresenting it.    But Moses said that if a young woman (the Hebrew here is Na'ara, not Almah) is found in the marriage bed not to be a virgin, that is, was not a virgin before laying with her husband, she is to be stoned to death.

So if the "almah" in Isa.7:14 is NOT a virgin, then she should be stoned to death before any child is born from her.  But that would have the Lord violating His own Law to use someone deserving of capital punishment in a miraculous sign.