Flexion

Part of speech: noun (n.)

1. The act of flexing or bending; a turning.

2. A bending; a part bent; a fold. Bacon.

3. Syntactical change of form of words, as by declension or conjugation; inflection. Express the syntactical relations by flexion. Sir W. Hamilton.

4. The bending of a limb or joint; that motion of a joint which gives the distal member a continually decreasing angle with the axis of the proximal part; -- distinguished from extension.