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

A set of chemically → identical  → atomic or → molecular entities.

→ chemical; → species.

A chemical species in which the → deuterium abundance is → enriched with respect to a mean standard value.

→ deuterated; → species.

1) A class of individuals having some common characteristics or qualities; distinct sort or kind.
2) Biology: The major subdivision of a genus or subgenus, regarded as the basic category of biological classification, composed of related individuals that resemble one another, are able to breed among themselves, but are not able to breed with members of another species.
3) Logic: One of the classes of things included with other classes in a genus. The set of things within one of these classes (Dictionary.com).

From L. species "a particular sort, kind, or type," originally "a sight, look, view, appearance," from specere "to look at, to see, behold;" PIE root spek- "to look around," → scope.

Âraz, from intensive/nuance â- + raz-, from Av. razan "order, → rule," from rāz- "to put in line, direct set," cf. Mod.Pers. raj "line, row," variants raž, rak, râk, rezg (Lori), radé, râdé "line, rule, row," rasté, râsté "row, a market with regular ranges of shops;" ris, risé "straight;" → right.