ball bearing

UK: /ˌbɔːlˈbɛərɪŋ/

WordReference Random House Learner's Dictionary of American English © 2025

ˈball ˈbear•ing, n. [countable]

1. Mechanical Engineering a small hard ball placed in a groove between two moving parts of a machine to allow the parts to move smoothly.

WordReference Random House Unabridged Dictionary of American English © 2025

ball′ bear′ing, [Mach.]

1. Mechanical Engineering a bearing consisting of a number of hard balls running in grooves in the surfaces of two concentric rings, one of which is mounted on a rotating or oscillating shaft or the like.
2. Mechanical Engineering any of the balls so used.

• 1880–85

ball′-bear′ing, adj. 

Collins Concise English Dictionary © HarperCollins Publishers::

ball bearing noun

1. a bearing consisting of a number of hard steel balls rolling between a metal sleeve fitted over the rotating shaft and an outer sleeve held in the bearing housing, so reducing friction between moving parts while providing support for the shaft
2. a metal ball, esp one used in such a bearing