What does Immanuel mean in Matthew 1:23?

Behold, a virgin--It should be "the virgin" meaning that particular virgin destined to this unparalleled distinction. shall be with child, and shall bring forth a son, and they shall call his name Emmanuel, which, being interpreted, is, God with us--Not that He was to have this for a proper name (like "Jesus"), but that He should come to be known in this character, as God manifested in the flesh, and the living bond of holy and most intimate fellowship between God and men from henceforth and for ever.

…He might have done so; for, by the law, a betrothed virgin, if she played the harlot, was to be stoned to death, Deu 22:23, Deu 22:24. But he was not willing to take the advantage of the law against her; if she be guilty, yet it is not known, nor shall it be known from him. How different was the spirit which Joseph displayed from that of Judah, who in a similar case hastily passed that severe sentence, Bring her forth and let her be burnt! Gen 38:24. How good it is to think on things…

Behold, a virgin shall be with child,.... These words are rightly applied to the virgin Mary and her son Jesus, for of no other can they be understood; not of Ahaz's wife and his son Hezekiah, who was already born, and must be eleven or twelve years of age when these words were spoken; nor of any other son of Ahaz by her or any other person since no other was Lord of Judea; nor of the wife of Isaiah, and any son of his, who never had any that was king of Judah.…