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

A slender, straight, generally pointed missile or weapon made to be shot from a bow and equipped with feathers at the end of the shaft near the → nock, for controlling flight (Dictionary.com). → Sagitta.

M.E. arewe, arwe, O.E. earh, possibly borrowed from O.N. ör; ultimately from PIE *arku- "bow and/or arrow," → arc.

Peykân "arrow, javelin" (cognate with afkan-, afkandan "to throw, cast away," parâkan-, parâkandan "to scatter, to disperse"), ultimately from Proto-Iranian *paiti-kan- "to throw against," from *paiti- "against, opposite, back" (cf. Mod.Pers. pâd- "against, contrary to;" Mid.Pers. pât-; O.Pers. paity "against, back, opposite to, toward, face to face, in front of;" Av. paiti; Skt. práti "toward, against, again, back, in return, opposite;" Pali pati-; Gk. proti, pros "face to face with, toward, in addition to, near;" PIE *proti) + *kan- "to throw."

Of little breadth or → width.

M.E., from O.E. nearu; cf. O.S. naru "narrow," Du. naar "unpleasant;" akin to Ger. Narbe "scar," literally, "narrow mark."

Bârik, from Mid.Pers. bârîk "narrow," from O.Iranian *bāra-ya-ka-, from stem *bāra- "to cut;" cf. Av. bāra- "edge, blade," in tiži-bāra- "sharp-edged," from brī- "to cut, shave, shear;" cf. Skt. bhrī- "to hurt, injure," bhrinanti "they hurt;" O.C.S. briti "to shave;" PIE base *bhrē- "to cut, pierce."

Optics: Of a filter, same as → interference filter.
Radio.: Encompassing a small frequency range, typically less than 300 Hz.

→ narrow; → band.

Photometry using narrow-band filters to isolate a particular spectroscopic line or molecular band.

→ narrow band; → photometry.

The outer region of a → quasar or an → active galactic nucleus displaying narrow spectral lines. Also called Type II AGN. See also → obscuring torus.

→ narrow; → line; → region.

The sequence of all natural processes in which the → entropy increases. In other words, the fact that these processes all move in one direction in time and are → irreversible. The past is distinctly different from the future; things always grow older, never younger.

→ time; arrow, M.E. arewe, arwe, from O.E. arwan, earh "arrow," from P.Gmc. *arkhwo (cf. Goth. arhwanza), from PIE base *arku- "bow and/or arrow," source of Latin arcus, → arc.

Peykân "arrow," → Sagitta; zamân, → time.