Flex"ion (?), n. [L. flexio: cf. F. flexion.] 1. The act of flexing or bending; a turning.

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

3. (Gram.) Syntactical change of form of words, as by declension or conjugation; inflection.

Express the syntactical relations by flexion.

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.

• The act of bending a joint, esp. a bone joint. The counteraction of extension.