apsis

[ ap-sis ]

noun

, plural ap·si·des [ap, -si-deez].

1. Astronomy. either of two points in an eccentric orbit, one higher apsis farthest from the center of attraction, the other lower apsis nearest to the center of attraction.
2. Architecture. an apse.

apsis

/ ˈæpsɪs; æpˈsaɪdəl; ˈæpsɪdəl /

noun

1. Also calledapse 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

apsis

/ ăp′sĭs /

, Plural apsides ăp′sĭ-dēz′

1. In the path of an orbiting body, either of the two points at which it is closest to or farthest away from the body it is orbiting.
2. See also apoapsis

Derived Forms

• apsidal, adjective

Word History and Origins

Origin of apsis¹

1595–1605; < Latin < Greek hapsís (felloe of ) a wheel, arch, vault, originally, fastening, equivalent to háp ( tein ) to fasten + -sis -sis

Word History and Origins

Origin of apsis¹

C17: via Latin from Greek; see apse

Example Sentences

The list of relics on the right of the apsis of Sta.

From Project Gutenberg

A reliquary, or case in which the relics of saints were kept. µ This word is also written apsis and absis.

From Project Gutenberg

The phenomenon of the progression of the apsides of an oval orbit, which is here alluded to, is familiar to all students in mechanics.

From Project Gutenberg

The line of the apsides has a slow forward angular motion in the plane of the planet's orbit, being retrograde only in the case of Venus.

From Project Gutenberg

The “line of apsides” is that which joins them, forming the major axis of the orbit.

From Project Gutenberg