ap·​sis | \ ˈap-səs How to pronounce apsis (audio) \
plural apsides\ ˈap-​sə-​ˌdēz How to pronounce apsis (audio) \

Definition of apsis

1 : the point in an astronomical orbit at which the distance of the body from the center of attraction is either greatest or least

First Known Use of apsis

1601, in the meaning defined at sense 1

History and Etymology for apsis

borrowed from Medieval Latin apsīs, apsīda "arc, vault," going back to Latin apsīd-, apsīs (also hapsīs, absīs) "arc described by a planet, segment of a circle," borrowed from Greek hapsīd-, hapsís (Ionic apsís) "loop, mesh, rim of a wheel, wheel, disk, segment cut off by a rainbow, arch, vault," from ap-s-, stem in noun derivation of háptein "to fasten," háptesthai "to fasten oneself to, grasp" + -īd-, -īs, noun suffix — more at haptics

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Cite this Entry

“Apsis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/apsis. Accessed 28 Feb. 2021.

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Britannica.com: Encyclopedia article about apsis

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