D defs.my
Entry 1 sense Webster, 1913

Training wheels

/trān'-ĭng wēlz/ · Train·ing wheels · IPA /ˈtreɪnɪŋ ˌ(h)wilz/
01 a pair of small wheels attached to the rear of a bicycle to keep the bicycle upright; -- used to assist those, especially small children, l…
  1. 1.
    a pair of small wheels attached to the rear of a bicycle to keep the bicycle upright; -- used to assist those, especially small children, learning how to ride a bicycle.