ball-and-socket joint

American  

[bawl-uhn-sok-it joint] / ˈbɔl ənˈsɒk ɪt ˌjɔɪnt /

noun

1. Also called enarthrosis.  Anatomy, Zoology. a joint in which the rounded end of one bone fits into a cuplike end of the other bone, allowing for relatively free rotary motion, as at the hip or shoulder.

2. Also called ball joint.  a similar joint between rods, links, pipes, etc., consisting of a ball-like termination on one part held within a concave, spherical socket on the other.

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ball-and-socket joint British  

noun

1. a coupling between two rods, tubes, etc, that consists of a spherical part fitting into a spherical socket, allowing free movement within a specific conical volume

2. Also called: multiaxial joint.  anatomy a bony joint, such as the hip joint, in which a rounded head fits into a rounded cavity, allowing a wide range of movement

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ball-and-socket joint Scientific  

/ bôl′ən-sŏk′ĭt /

1. A joint, such as the shoulder or hip joint, in which a spherical knob or knoblike part of one bone fits into a cavity or socket of another, so that some degree of rotary motion is possible in every direction.

2. A mechanical device consisting of a spherical knob at the end of a shaft that fits securely into a socket. Ball-and-socket joints are used to connect parts of a machine that require rotary movement in nearly all directions. Ball-and-socket joints allow the front wheels of a car to be turned by the steering mechanism.

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Etymology

Origin of ball-and-socket joint

First recorded in 1660–70

Example Sentences

Those fingers come with a long, skeletal middle digit equipped with a ball-and-socket joint for horrifying dexterity, like the Ghost of Christmas Yet to Come beckoning Ebenezer Scrooge to gaze upon his own sordid death.

From Salon • May 11, 2025

Dr. Günther compares it to a ball-and-socket joint, except there is no socket.

From New York Times • Aug. 31, 2021

A ball-and-socket joint in its jaw allows a fang to swivel out and snag an unsuspecting victim without the reptile ever opening its mouth.

From National Geographic • May 5, 2018

Like its cousin the Hispaniolan solenodon, whose snout sits on a ball-and-socket joint, it is an evolutionary curiosity.

From The New Yorker • May 24, 2017

It is a bath that can be rocked, or inclined in any direction, for its center rests upon a ball-and-socket joint.

From Scientific American Supplement, No. 315, January 14, 1882 by Various