Charles Ellicott Commentary Genesis 2:21

"And Jehovah God caused a deep sleep to fall upon the man, and he slept; and he took one of his ribs, and closed up the flesh instead thereof:" — Genesis 2:21 (ASV)

And the Lord God caused a deep sleep (compare to Job 4:13, where it is the same word) to fall upon Adam—in Hebrew, "the man."

One of his ribs.—The word is never translated rib except in this place, but always side, flank. This is also the true meaning of the Latin word costa, by which it is rendered in the Vulgate, as shown in the French côte, and our word coast. Both the Greek and Syriac also translate it with words that primarily signify the side, but derivatively the rib.

Woman was not formed out of one of man’s many ribs, the loss of which he would not feel. She is one side of man; and though he may have several sides to his nature and character, yet without woman one integral portion of him is lacking.

Closed up the flesh instead thereof.—Literally, closed up flesh under it, that is, in its place. This does not mean that man now has flesh where before he had this side, but that a cavity was prevented by drawing the flesh on the two edges close together. Metaphysically, it means that man has no compensation for what was taken from him, except in the woman, who is the one side of his nature which he has lost.