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

An → integer that is equal to the → sum of its → positive  → divisors, not including itself. For example 6, because its positive divisors are 1, 2, and 3, and 1 + 2 + 3 = 6. Two other examples are 28 and 496.

→ perfect; → number.

A → positive integer that can be expressed as an integer → power of another positive → integer. For example, n is a perfect power if there exist natural numbers m> 1, and k> 1 such that m^k = n. → perfect cube, → perfect square.

→ perfect; → power.

A set P is called perfect if P = P', where P' is the derived set of P.

→ perfect; → set.

An → integer of the form n², where n is a → positive number. In other words, a → perfect power when k = 2.

→ perfect; → square.

Capable of becoming or of being made perfect.

→ perfect; → -able.

The state or quality of being or becoming perfect.

→ perfect; → -tion.

1) Any of various doctrines holding that religious, moral, social, or political perfection is attainable.
2) A personal standard, attitude, or philosophy that demands perfection and rejects anything less (Dictionary.com).

→ perfection; → -ism.

1) A person who adheres to or believes in → perfectionism.
2) A person who demands perfection of himself, herself, or others (Dictionary.com).

→ perfection; → -ist.

1) To carry out; → execute; do.
2) To go through or execute in the proper, customary, or established manner (Dictionary.com).

M.E. parformen, from Anglo-Fr. performer, from O.Fr. parfornir "to do, carry out, finish, accomplish," from par- "completely," → per-, + fornir "to provide."

Pergâlidan, from Kurd. (Sanandaj) pergâl "work, doing; order, command," ultimately from Proto-Ir. *parikar-, from *pari- "through, throughout; thoroughly" (O.Pers. pariy "around, about;" Av. pairi "around, over") + *kar- "to do;" Pers. kar-, variants kâr, gar, gâr, → work.

1) The act of performing a ceremony, play, piece of music, etc.
2) The execution or accomplishment of work, acts, feats, etc.
3) A musical, dramatic, or other entertainment presented before an audience (Dictionary.com).

→ perform; → -ance.

1) Relating to or of → performance, especially of dramatic or artistic performance.
2) A → performative utterance.

→ perform; → -ive.

A sentence or expression which is not only describing a given reality, but actually does or accomplishes something. For example "I now declare you husband and wife" (when uttered by the authorized officiator during a marriage ceremony).

→ performative; → utterance.

1) Someone who performs in front of an audience, for example an actor or musician.
2) Someone who does something with a particular amount of success (Macmillan Dictionary).

→ perform; → -er.

A prefix meaning "about, around" (perimeter, periscope), "enclosing, surrounding" (pericardium), and "near" (perigee, perihelion).

From Gk. peri "around, about, beyond;" cognate with Pers. pirâ-, as below.

Pirâ-, variant par- "around, about," from Mid.Pers. pêrâ; O.Pers. pariy "around, about," Av. pairi "around, over," per- "to pass over, beyond;" cf. Skt. pari; Indo-Iranian *pari- "around;" PIE base *per- "through, across, beyond;" cf. Gk. peri "around, about, beyond;" L. per "through."

The point in an orbit of a body where it is closest to its primary; opposite of → apoapsis.

→ peri- + → apsis.

In a binary system, the point in the orbit where a component is nearest the other component; opposite of → apastron.

→ peri- + astron; → astro-.

The point in the orbit of one component of a binary system which is closest to the center of mass of the system; opposite of → apocenter.

→ peri- + → center.

The point in the orbit of a satellite around the Moon closest to the Moon; opposite of → apocynthion.

→ peri- + Gk. Cynthia "goddess of the Moon;" → Cynthian.

Pirâmâh, from pirâ-, → peri-, + mâh→ moon.

Of or pertaining to a → perigalacticon.

→ peri-; → galactic.

The point in an object's orbit around a galaxy when the object lies closest to the galactic center; opposite of → apogalacticon.

→ peri- + → galaxy.