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ap·sis (ăpsĭs)
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n. pl. ap·si·des (-sĭ-dēz′)
1. Architecture An apse.
2. Astronomy The point of greatest or least distance of the orbit of a celestial body from the center of mass of the system.
[Late Latin, from Latin, arch, vault, from Greek hapsis, from haptein, to fasten.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. 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.

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