sprain

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A painful wrenching or laceration of the ligaments of a joint.
• noun The condition resulting from a sprain.
• transitive verb To cause a sprain to (a joint or ligament).

from The Century Dictionary.

• To press; push.
• To overstrain, as the muscles or ligaments of a joint so as to injure them, but without luxation or dislocation.
• noun A violent straining or wrenching of the soft parts surrounding a joint, without dislocation.
• noun The injury caused by spraining; a sprained joint.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act or result of spraining; lameness caused by spraining.
• noun (Med.) the separation of a tendon from its point of insertion, with the detachment of a shell of bone to which the tendon is attached.
• transitive verb To weaken, as a joint, ligament, or muscle, by sudden and excessive exertion, as by wrenching; to overstrain, or stretch injuriously, but without luxation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The act or result of spraining; lameness caused by spraining; as, a bad sprain of the wrist.
• verb 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.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb twist suddenly so as to sprain
• noun a painful injury to a joint caused by a sudden wrenching of its ligaments