ball-and-sock·et joint
noun/ˌbɔːl ən ˈsɒkɪt dʒɔɪnt/
/ˌbɔːl ən ˈsɑːkɪt dʒɔɪnt/
(anatomy)- a joint such as the hip joint at the top of the leg, in which a piece of bone in the shape of a ball moves inside a curved hollow part
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球窝关节;杵臼关节