An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The moment when the center of the Sun crosses the meridian. Same as true noon.

→ apparent; → noon.

Same as → apparent position.

→ apparent; → place.

1) The position on the celestial sphere at which a heavenly body would be seen from the Earth at a particular time.
2) A position given by the coordinates calculated for a star, if it were seen from the Earth's centre, relative to the → real equator and the → real equinox, at a certain date. It includes the displacements from one heliocentric direction, given in a stellar catalogue, due to → precession, → nutation, → aberration, → proper motions, → annual parallax, and light gravitational deviation (M.S.: SDE).

→ apparent; → position.

The instant of time when the object is in the East and the geometric → zenith distance is equal to 90° plus the → horizontal refraction plus the semidiameter minus the → parallax.

→ apparent; → rising.

The instant of time when the object is in the West and the geometric → zenith distance is equal to 90° plus the → horizontal refraction plus the semidiameter minus the → parallax.

→ apparent; → setting.

The time interval between two successive → upper transits of the → true equinox of date.

→ apparent; → sidereal; → day.

The → mean sidereal time corrected for the → nutation and shift in the obliquity of the ecliptic that occurs as a result of the Moon's gravitational effect. Apparent sidereal time differs from mean sidereal time in that the → true vernal equinox point is used.

→ apparent; → sidereal; → time.

The duration of one rotation of the Earth on its axis (→ Earth's rotation), with respect to the → apparent Sun. It is measured by successive transits of the apparent Sun over the lower branch of a → meridian.

→ apparent; → solar day.

The time based on the motion of the → apparent Sun and kept by dividing the day into 24 equal hours.

→ apparent; → solar; → time.

The → true Sun as seen by an observer on Earth. The term "apparent Sun" is used in contrast to → mean Sun, which refers to an average of the Sun's position). See also: → apparent solar time and → mean solar time.

→ apparent; → Sun.

→ Apparent magnitude in the visual wavelengths, around 5600 Å. → visual magnitude.

→ apparent; → visual; → magnitude.

Judging from what is apparent. As far as one knows or can see.

→ apparent; → -ly.

A software with a specific function, such as a word processor or game. Contrast with operating system software.

→ application; → software.

1) Arrest (someone) for a crime.
2) → Understand or → perceive. Often to hold in opinion but without positive certainty.

From L. apprehendere "to take hold of, grasp," from → ad- "to" + prehendere "to seize," → prehend.

1) Anxiety or fear that something bad or unpleasant will happen.
2) Understanding; grasp.
3) The action of arresting someone (Oxford Dictionary, lexico.com).

Verbal noun of → apprehend.

→ advance of perihelion, → relativistic precession.

→ apsidal; → precession.

1) In → graph theory, a → rooted tree that has a natural orientation in which all → paths are directed away from the → root. More specifically, a → directed graph in which, for a → vertex u, called the → root, and any other vertex v, there is exactly one → directed path from u to v.
2) Biology: The state of being branched, or treelike, in structure, appearance, growth, or other properties.

From Fr. arborescence, from → arborescent + → -ance.

Šâkedâri, nous from šâkedâr, → arborescent.

Having the shape or characteristics of a tree in growth, structure, or appearance.

From Fr. arborescent, from L. arborescent-, p.p. of arborescere "to grow into a tree," from arbor, arboris "tree."

Šâkedâr "having branches," from šâké, from šâxé, → branch, + dâr "having, possessor," from dâštan "to have, to possess," → charged.

1) The art or practice of designing and building structures.
2) Computers: The arrangement of the various devices in a computer system or network. See also → software architecture.

M.E., from M.Fr. architecture, from L. architectura, from architectus "architect," from Gk. arkhitekton "master builder, director of works," from arkhi- "chief" + tekton "builder, carpenter," → technique.

Mehrâzik, from mehrâz literally "chief mason," from meh- "great, large," → high, + râz "mason, builder" (Borhân-e Qâte'), from Mid.Pers. râz "builder, architect," probably related to O.Pers. râs-, Av. râz- "to direct, set, put in line" (with many cognates in Pers., such as râst "straight, direct, true;" raj, rak, râk, rezg (Lori), radé, râdé "line, rule, row," rasté, râsté "row, a market with regular ranges of shops;" ris, risé "straight"); cf. Skt. raj- "to direct, stretch," rjuyant- "walking straight;" Gk. orektos "stretched out;" L. regere "to lead straight, guide, rule," p.p. rectus "right, straight;" Ger. recht; E. right; PIE base *reg- "move in a straight line," hence, "to direct, rule;" + -ik, → -ics.

A particular extent of space or surface; the scope of a concept, operation, or activity.

The etymology is not clear; perhaps akin to L. arere "to be dry" → arid.

Pahné "area, field," from pahn "broad, wide" (Mid.Pers. pah(a)n, Av. pathana- "broad, wide, spacious," probably related to perethav- "broad, wide," Skt. prthav-, Gk. platus; PIE *plat- "to spread") + noun forming suffix -é.