sprain

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A painful wrenching or laceration of the ligaments of a joint.
2. n. The condition resulting from a sprain.
3. v. To cause a sprain to (a joint or ligament).

Century Dictionary and Cyclopedia

1. To press; push.
2. To overstrain, as the muscles or ligaments of a joint so as to injure them, but without luxation or dislocation.
3. n. A violent straining or wrenching of the soft parts surrounding a joint, without dislocation. The ordinary consequence of a sprain is to produce some degree of swelling and inflammation in the injured part.
4. n. The injury caused by spraining; a sprained joint.

Wiktionary

1. n. The act or result of spraining; lameness caused by spraining; as, a bad sprain of the wrist.
2. v. To weaken, as a joint, ligament, or muscle, by sudden and excessive exertion, as by wrenching; to overstrain, or stretch injuriously, but without luxation; as, to sprain one's ankle.

GNU Webster's 1913

1. v. To weaken, as a joint, ligament, or muscle, by sudden and excessive exertion, as by wrenching; to overstrain, or stretch injuriously, but without luxation.
2. n. The act or result of spraining; lameness caused by spraining.

WordNet 3.0

1. v. twist suddenly so as to sprain
2. n. a painful injury to a joint caused by a sudden wrenching of its ligaments