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

In an → isolated system, any initial state will occur again in the course of the → evolution of the system over a sufficiently long but finite → time.

→ Poincaré sphere; → recurrence; → theorem.

1) A person or thing that comes before another of the same kind; a forerunner.
2) A substance from which another is formed, especially by metabolic reaction (OxforddDctionaries.com)

M.E., from L. præcursor "forerunner," from præcursus, p.p. of præcurrere, from præ- "before," → pre-, + currere "to run," → current.

Pišgâm, from piš- "before," → pre-, + gâm "step, pace," → stage.

A component of a → pulsar pulse that appears shortly in advance of the main pulse.

→ precursor; → pulse.

To occur again, as an event, experience, etc.

From L. recurrere "to return, run back," → re- + currere "to run," → current.

Bâzâmadan "to come back, return," from bâz, → re-, + âmadan "to come, arrive, become" (present stem ây-); Av. ay- "to go, to come," aēiti "goes;" O.Pers. aitiy "goes;" Skt. e- "to come near," eti "arrival;" L. ire "to go;" Goth. iddja "went;" Lith. eiti "to go;" Rus. idti "to go."

1) An act or instance of recurring.
2) Return to a previous condition, habit, subject, etc. (Dictionary.com). → recurrence relation.

Verbal noun of → recur.

A → sequence based on a → rule that gives the next → term as a → function of the previous term(s). For example, the sequence 3, 9, 21, 45,... can be represented by the recurrence relation u_n+1 = 2u_n + 3, where u₁ = 3 and n ≥ 1.

→ recurrence; → relation.

Occurring or appearing again, especially repeatedly or periodically (Dictionary.com). → recurrence nova.

Verbal adj. from → recur.

A → cataclysmic variable star that undergoes → outbursts similar to those found in novae.

→ recurrent; → nova.

1) A running backward, return.
2) Math.: A process in which objects are defined by the repeated application of a rule or algorithm.

From L. recursionem (nominative recursio); → recurrent.

Bâzâneš, verbal noun of bâzâmadan, → recur.

1) Pertaining to or using a rule or procedure that can be applied repeatedly.
2) Math.: Pertaining to or using the process of → recursion.

Adjective from → recursion.

Math.: A definition of a function from which values of the same function can be calculated in a finite number of steps. In mathematical logic and computer science, a recursive definition is used to define an object in terms of itself. An example is the → factorial: n! = n*(n-1)!

→ recursive; → definition.