Flexure

noun

1. The act of bending or flexing; flexion.
2. A turn; a bend; a fold; a curve.
3. A curve or bend in a tubular organ.
4. The last joint, or bend, of the wing of a bird.
5. The small distortion of an astronomical instrument caused by the weight of its parts; the amount to be added or subtracted from the observed readings of the instrument to correct them for this distortion.