He . . . did not care a pin for her.
Spectator.
4. That which resembles a pin in its form or use; as: (a) A peg in
musical instruments, for increasing or relaxing the tension of the
strings. (b) A linchpin. (c) A rolling-pin. (d) A clothespin. (e)
(Mach.) A short shaft, sometimes forming a bolt, a part of which serves
as a journal. See Illust. of Knuckle joint, under Knuckle. (f)
(Joinery) The tenon of a dovetail joint.
5. One of a row of pegs in the side of an ancient drinking cup to mark
how much each man should drink.
6. The bull's eye, or center, of a target; hence, the center. [Obs.]
"The very pin of his heart cleft." Shak.