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

The Sun during its 11-year cycle of activity when spots, flares, prominences, and variations in radiofrequency radiation are at a maximum.

→ active; → sun.

1) The doctrine or practice of vigorous action or involvement as a means of achieving political or other goals, sometimes by demonstrations, protests, etc. (Dictionary.com). See also → activist.
2) Philosophy: a) A theory that the essence of reality is pure activity, especially spiritual activity, or process. b) A theory that the relationship between the mind and the objects of perception depends upon the action of the mind (Dictionary.com).

→ active; → action; → -ism.

An especially active, vigorous advocate of a cause, especially a political cause (Dictionary.com).

Agent noun from → activism.

For a radioactive substance, the average number of atoms disintegrating per unit time.

Activity, from → active + -ity.

Žirandegi, noun from žirandé, → active.

1) One who takes part; a participant.
2) A theatrical performer.

→ act + → -or.

1) Existing in act or fact; real.
2) Philosophy: The character of what is realized in act (such as a statue), as opposed to what can potentially be realized (from a piece of rock).

M.E. actuel, from O.Fr. actuel "now existing, up to date," from L. actualis "active, pertaining to action," adj. form of actus, → act.

Žirvand, from žir, → act, + -vand a suffix forming adjectives denoting "possessed of, similarity, relation," variants -âvand, -van (e.g. xodâvand "possessor, master," pulâdvand "hard as steel, name of a hero," dowlatvand "rich," setarvan "mule-like, barren," polvan "bridge-like, a raised path"), from Mid.Pers. -âwand (hunarâwand "skilled," warzâwand "powerful"); Av. -vant (aurvant- "swift," surunvant- "audible"); cf. Skt. -vant (amavant- "having attacking power").

1) The quality or state of being actual or something that is actual; reality.
2) Philosophy: According to Aristotle, what has → form and can causally interact with other things, as opposed to → potentiality.

→ actual; → -ity.

The act or process of actualizing.

Verbal noun of → actualize; → -tion.

To make actual or real; turn into action or fact.

→ actual; → -ize.

1) To put into mechanical action or motion.
2) To incite or move to action; motivate.

From L. actuatus, p.p. of actuare, from actus, → act.

Baržiridan, from bar- "on, upon, up," → on-, + žiridan "to → act."

The act or process of putting into action; activation.

Verbal noun of → actuate.

A mechanism to activate process control equipment by use of pneumatic, hydraulic, or electronic signals.

→ actuate; → -or.

1) Electronics: The extent to which an → analogue → amplifier boosts the strength of a → signal. Also called → gain.
2) In → gravitational lensing, the ratio of the lensed brightness to unlensed brightness. This factor depends on the mass of the → lensing object and the closeness of the alignment between observer, lens, and source (→ impact parameter).

→ amplification; → factor.

The angle between the direction in which a ray is refracted and the normal to the refracting surface.

→ angle; → refraction.

Of or pertaining to an → apogalacticon.

→ apo-; → galactic.

The point at which a celestial body is farthest from the center of a galaxy; opposite of → perigalacticon.

From → apo- "away from, off" + galacticon, → galaxy.

From apâ, → apo-, + kahkašân, → galaxy.

1) An object made by a human being, typically one of cultural or historical interest.
2) Something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure (OxfordDictionary.com).

From It. artefatto, from L. arte "by skill" (ablative of ars "→ art") + factum "thing made," from facere "to make, do," → -fy.

Dasâc "hand made," from das variant of dast, → hand, + sâc, variant of sâz-, sâxtan, → agree.

The → angular → displacement of a point on the → celestial sphere due to the Earth's → atmospheric refraction.

→ astronomical; → refraction.

The shift in apparent direction of a celestial object caused by the bending of light while passing through the Earth's atmosphere. Since the density of the atmosphere decreases with altitude, the starlight will bend more as it continues down through the atmosphere. As a result, a star will appear higher in the sky than its true direction.

→ atmospheric; → refraction.

The ratio of the radiation intensity after traversing a layer of matter to its intensity before.

→ attenuation; → factor.