apsis

apsis

1. either of two points lying at the extremities of an eccentric orbit of a planet, satellite, etc., such as the aphelion and perihelion of a planet or the apogee and perigee of the moon. The line of apsides connects two such points and is the principal axis of the orbit

2. another name for apse

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

apsis

[′ap·səs]

(astronomy)

In celestial mechanics, either of the two orbital points nearest or farthest from the center of attraction. Also known as apse.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

apsis

The semicircular termination of any rectangular chamber; an apse.

McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.