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sim·plex (sĭmplĕks)
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adj.
1. Consisting of or marked by only one part or element.
2. Of or relating to a telecommunications system in which only one message can be sent in either direction at one time.
n. pl. sim·plex·es or sim·pli·ces (-plĭ-sēz)
1. Mathematics A Euclidean geometric spatial element having the minimum number of boundary points, such as a line segment in one-dimensional space, a triangle in two-dimensional space, or a tetrahedron in three-dimensional space.
2. Linguistics A word that has no affixes and is not part of a compound; a simple word.

[Latin, simple; see sem-1 in the Appendix of Indo-European roots.]

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.