D defs.my
Entry 1 sense Webster, 1913

Racktail

/(răk"tāl`)/ · Rack·tail · IPA
01 n. An arm attached to a swinging notched arc or rack, to let off the striking mechanism of a repeating clock.
  1. 1.
    An arm attached to a swinging notched arc or rack, to let off the striking mechanism of a repeating clock.(Horol.)