| Term | Definition |
| J | joule |
| jaundice | Yellowing of the skin and eyes due to excessive bilirubin in body |
| jaw | Bony structure of the mouth consisting of the mandible and the maxilla. |
| jealous | Fearful of the loss of affection or position. |
| jejun/o | jejunum (second part of the small intestines) |
| jejunal | Pertaining to the jejunum |
| jejunum | Part of the small intestine, connecting the duodenum to the ileum. |
| jerk | A sudden involuntary movement. |
| JOD | juvenile onset diabetes |
| joint capsule | The sac surrounding a joint. It is composed of an outer fibrous articular capsule and an inner synovial membrane. |
| joints | The points of connection between the ends of certain bones. Also known as articulations |
| JRA | juvenile rheumatoid arthritis |
| jt. | joint |
| jug- | yoke |
| jugular veins | Large veins in the neck which return blood from the brain, face, and neck to the heart. Each side of the neck has two jugular veins, external and internal. |
| juxta- | near, close |
| JVD | jugular venous distention |
| JVP | jugular venous pulse |