Webster’s Revised Unabridged Dictionary · 1913
Treadle
Trea′dle (trĕd′'l), n. [OE. tredyl a step, AS. tredel. See Tread.] 1. The part of a foot lathe, or other machine, which is pressed or moved by the foot.
2. (Biol.) The chalaza of a bird's egg; the tread.