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de·cus·sate (dĭ-kŭsāt, dĕkə-sāt)
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tr. & intr.v. de·cus·sat·ed, de·cus·sat·ing, de·cus·sates
To cross or become crossed so as to form an X; intersect.
adj.
1. Intersected or crossed in the form of an X.
2. Botany Arranged on a stem in opposite pairs, at right angles to those above or below: decussate leaves.

[Latin decussāre, decussāt-, from decussis, the number ten, intersection of two lines (from the Romans' use of X for the numeral 10), a ten-as coin : decem, ten; see dek in the Appendix of Indo-European roots + assis, as (coin).]

de·cussately adv.
(click for a larger image)
decussate

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
 

Indo-European & Semitic Roots Appendices

    Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:

    Indo-European Roots

    Semitic Roots

    The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.