Yechidah · יחידה — the one that is not in a pairיחידה

⭐⭐ Ask the Midrash why this one is called the single one, and the answer is not mystical at all. It is anatomical.

Bereshit Rabbah 14:9: it is called yechidah because everything else in the body comes in twos and this does not. Two eyes. Two ears. Two nostrils. Two hands, two feet, two lungs, two kidneys. And one of this.

You can check it on yourself in about four seconds, which is exactly the sort of argument the fifth century liked and the sixteenth century stopped making.

Because a thousand years later the same word means something else entirely: the point of a person that is not merely close to God but continuous with the divine — the level at Keter, above the reach of any faculty, the part that was never in exile and cannot be damaged. It is what devekut is reaching for. Keter's own entry has carried this level in its soul: line all along; that line stays the source and is not restated here.

Both readings are in this app, dated, and neither is corrected into the other. One is a count of your paired organs. One is the last thing in you that is God's. They are the same word.