apsis

ap·sis  (pss)

n. pl. ap·si·des (-s-dz)

1. Architecture An apse.

2. Astronomy The point of greatest or least distance of the orbit of a celestial body from a center of attraction.

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[Late Latin, from Latin, arch, vault, from Greek hapsis, from haptein, to fasten.]

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apsis [ˈæpsɪs]

n pl apsides [æpˈsaɪdiːz ˈæpsɪˌdiːz]

1. (Astronomy) Also called apse 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. (Fine Arts & Visual Arts / Architecture) another name for apse [1]

[via Latin from Greek; see apse]

apsidal  [æpˈsaɪd^əl ˈæpsɪd^əl] adj

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apsis  (pss)

Plural apsides (ps-dz)

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. See also apoapsisperiapsis

Thesaurus

Noun

1.

apsis - a domed or vaulted recess or projection on a building especially the east end of a church; usually contains the altar apse church building, church - a place for public (especially Christian) worship; "the church was empty" niche, recess - an enclosure that is set back or indented tribune - the apse of a Christian church that contains the bishop's throne