decussation
(dɛkʌˈseɪʃən)
[ad. L. decussātiōn-em, n. of action f. decussāre: see decuss and -ation.]
Crossing (of lines, rays, fibres, etc.) so as to form a figure like the letter X; intersection.
| 1656 in Blount Glossogr. 1658 Sir T. Browne Gard. Cyrus i. 37 The letter χ, that is the Emphatical decussation, or fundamental figure. 1662 Evelyn Chalcogr. (1769) 90 Performed in single and masterly strokes, without decussations, and cross hatchings. 1672 Newton in Rigaud Corr. Sci. Men (1841) II. 344 By the iterated decussations of the rays, objects will be rendered less distinct. 1713 Derham Phys. Theol. iv. ii. 95 A Coalition or Decussation of the Optick Nerves. 1839–47 Todd Cycl. Anat. III. 480/1 The point at which the decussation [of nerve-fibres in the brain] takes place is about ten lines below the margin of the pons Varolii. |
b. Rhet. An arrangement of clauses, etc. in which corresponding terms occur in reverse order; chiasmus.
| 1841 Tait's Mag. VIII. 561 They have..become weary of these pretty grammatico-metrical cuttings and decussations. |
¶ Erroneous use, app. for decussion, striking off.
| 1654 H. L'Estrange Chas. I (1655) 117 He yeilded his head to de-cussation, to the striking off. |