Flexion

1. The act of flexing or bending; a turning.
2. A bending; a part bent; a fold.
3. (Gram.) Syntactical change of form of words, as by declension or conjugation; inflection.
4. (Physiol.) 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.