Ball-and-socket joint: A joint in which the round end of a bone fits into the cavity of another bone. The hip joint is a ball-and-socket joint. QUESTION The term arthritis refers to stiffness in the joints. See Answer From Arthritis Resources Inside the Visit With a RheumatologistTreating Psoriatic Disease With BiologicsRA and Your Joints Featured Centers Good and Bad Foods for PsoriasisVideo: Getting Personal on Life With MS Health Solutions From Our Sponsors Shot-Free MS Treatment Your Child and COVID-19
