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

Same as → stream tube.

→ flow; → tube.

The ability of a body of matter (liquid, gas, loose particulate solid) to flow.

From flowable, adj. from → flow + → -able + → -ity.

Tacandegi, from tacandé (originally tacandag), agent noun of tacidan, → flow, + noun suffix -i.

To change continually; to shift back and forth; vary irregularly; to rise and fall in or as if in waves.

From L. fluctuationem (nom. fluctuatio), from fluctuare "to undulate," from fluctus "wave," from p.p. of fluere "to flow."

Verbal form of oftâxiz, → fluctuation.

Continual rise and fall.

Verbal noun of → fluctuate.

Oftâxiz "fall and rise," from oft "fall" stem of oftâdan "to fall" (Mid.Pers. opastan "to fall," patet "falls;" Av. pat- " to fly, fall, rush," patarəta- "winged;" cf. Skt. patati "he flies, falls," pátra- "wing, feather, leaf;" Gk. piptein "to fall," pterux "wing;" L. penna "feather, wing;" O.E. feðer "feather;" PIE base *pet- "to fly, rush") + -â- interfix + xiz present stem of xâstan, xizidan "to rise, get up" (Mid.Pers. xyz- "to stand up, rise;" Proto-Iranian *xiz- "to rise, ascend; increase").

1) Light, downy particles, as of cotton.
2) A soft, light, downy mass (Dictionary.com).

Apparently a variant of floow "wooly substance, down, nap," perhaps from Flemish vluwe, from Fr. velu "shaggy, hairy," from L. vellus "fleece," or L. villus "tuft of hair" (Online Etymology Dictionary).

Kork "down, soft wool, fluff," of unknown etymology.

Of, resembling, or covered with fluff.
2) Light or airy (Dictionary.com).

From → fluff + -y adj. suffix, from O.E. -ig, cognate with L. -icus, → -ic.

Korkvâr "resembling fluff," with -vâr, a suffix of possession, similarity, and aptitude (e.g., omidvâr, sezâvâr, sugvâr, šâhvâr, gušvâr), → -oid; korki adj. with -i.

An aggregate of small particles loosely stuck together. Same as → porous dust grain.

→ fluffy; → dust; → grain.

A continuous, amorphous substance whose molecules move freely past one another and that has the tendency to assume the shape of its container; collective term for liquids and gases.

From L. fluidus "fluid, flowing," from fluere "to flow;" → flux.

Šârré, from šârr, → flux.

The branch of → fluid mechanics that deals with the movement of gases and liquids.

→ fluid; → dynamics.

The branch of physics that extends the ideas developed in → mechanics and → thermodynamics to the study of motion and equilibrium of → fluids.

→ mechanics; → fluid.

The ability of a substance to flow; reciprocal of → viscosity.

→ fluid + → -ity.

A type of → luminescence in which photons of lower energy are emitted as the result of absorption of energy by an atom or molecule from other radiation. The phenomenon lasts as long as the stimulus responsible for it is present.

Coined by English mathematician and physicist Sir George G. Stokes (1819-1903) from fluor-, from → fluorspar, + → -escence, a suffix of nouns denoting action or process, change, state or condition, etc.

Possessing the property of → fluorescence.

→ fluorescence; → -escent.

A tubular → electric discharge lamp in which light is produced by the → fluorescence → phosphors coating the inside of the tube.

→ fluorescent; → lamp.

A compound (salt of hydrofluoric acid) containing → fluorine.

→ fluorine; → -id.

Gaseous chemical element; symbol F. It is the most reactive of all chemical elements. It is a yellowish, corrosive gas, which reacts with most organic and inorganic substances. → Atomic number 9; → atomic weight 18.9984; → melting point -219.62 °C; → boiling point -188.14 °C; → density 1.696 grams per liter at STP; → valence -1. Fluorine and its compounds are used in producing uranium (from the → hexafluoride) and more than 100 commercial fluorochemicals, including many high-temperature plastics.

From L. fluere "flow, → flux," since fluorspar (CaF₂) was used as a flux in metallurgy because of its low melting point. It was discovered in hydrofluoric acid by the Swedish pharmacist and chemist Carl-Wilhelm Scheele in 1771 but it was not isolated until 1886 by the French pharmacist and chemist Ferdinand Moisson.

A → mineral composed of calcium fluoride, CaF₂, also called → fluorspar, that is often → fluorescent under → ultraviolet light.

From fluor-, → fluorine, + → -ite.

Same as → fluorite.

From fluor-, → fluorine, + spar "a crystalline mineral."

The amount of energy, fluid, or particles passing in a given direction in a unit of time.

O.Fr. flux, from L. fluxus, p.p. of fluere "to flow," PIE base *bhleug- (cf. L. flumen "river;" Gk. phluein "to boil over, bubble up," phlein "to abound").

Šâr "outpouring of water, wine, etc.," šâridan "to flow (as rivers), with a great noise; to pour," âbšâr "waterfall;" saršâr "overflowing; brim-full;" Ossetic ægzælyn "to pour down;" Pashto zγâstəl/zγâl- "to swim;" Av. γžār- "to flow;" cf. Skt. ksar- "to flow;" Gk. phtheirein "to destroy, perish."

The → calibration of the flux received by a detector in terms of absolute units.

→ flux; → calibration.