apsis

ap·sis

noun \ˈap-səs\

plural ap·si·des\-sə-ˌdēz\

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

2

: apse 2

Origin of APSIS

New Latin apsid-, apsis, from Latin, arch, orbit, from Greek hapsid-, hapsis, from haptein to fasten

First Known Use: 1658