A-CH-D – ‘#1; summit, end point of division’

I. אחך , one. The root חך, from which this word is formed, and which is sometimes taken for unity itself, particularly in Chaldaic, signifies literally, a point, a summit, the sharpest part of a thing; the top of a pyramid. It is division arrested, subjugated by a sort of effort; as the two signs ד and ח which compose it, indicate. In the feminine it is written אחת. (d’Olivet)