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

Denoting a → function that is defined on a sequence of → intervals or pieces. For example: |x| = -x for x < 0, x = 0 for x = 0, and x = x for x > 0.

→ piece, + -wise, → clockwise.

A function f(x) in an interval if :1) the interval can be divided into a finite number of pieces in each of which f(x) is continuous, and 2) the limits of f(x) as x approaches the boundary point of each piece are finite. In other words, a piecewise continuous function is one that is made up of a finite number of continuous pieces.

→ piecewise; → continuous; → function.

The property exhibited by some crystals (notably quartz) that develop an electric charge or potential difference across them when subjected to mechanical strain; and conversely produce mechanical forces when a voltage is applied to them in a suitable manner.

From piezo-, from Gk. piezein "to press tight" + → electric; → effect.

oskar, → effect; fešârbarqi pertaining to fešârbarq, from fešâr, → pressure, + barq, → electricity.

An assemblage of things laid or lying one upon the other (Dictionary.com).

M.E., from M.Fr. pile and directly from L. pila "pillar, mole of stone."

Tal "heap; hill," maybe related to Gk. tylos "a hard and thickened area on the skin, callus, lump," tymbos "burial mound, grave, tomb;" Av. tuma- "fat;" L. tumere "to swell," tumulus "raised heap of earth," tumidus "swollen;" tumor "a swelling."

An elongated structure often found at the interface between an → H II region and its associated → molecular cloud. Also called → elephant trunk. The most famous examples are the "pillars of creation" in the → Eagle Nebula, which are several → light-years in length. There are indications for star formation at the tips of the pillars. In general the pillars point like fingers toward the young → massive stars ionizing the nebula. Most of the mass is concentrated in the head which has a bright rim facing the young stars.

M.E. pillare, O.Fr. piler, from M.L. pilare, from L. pila "pillar, stone barrier."

Sotun "pillar," → column.

The component of a → planispheric astrolabe that is inserted in the back of the → mater. The pin enables the main parts of the instrument (the → alidade, the → rete, and the → rule) to rotate freely around the common center of the mater and the → tympanum (online museo galileo, VirtualMuseum).

M.E. pinne, from O.E. pinn "peg, bolt," from L. pinna "a feather, plume."

&ACIRC;sé, → axis.

The constriction of a current-carrying plasma column caused by its external self-magnetic field.

M.E. pinch, from O.Fr. pincier "to pinch," possibly from V.L. *punctiare "to pierce," from L. punctum "point," and *piccare "to pierce."

Penk "pinch, squeezing or compressing between the finger and thumb" (Dehxodâ), cf. (Tabari) pendik, pecelik, (Kermâni) perenju "pinch," maybe related to panjé "the palm of the hand with five fingers; fist," from panj "five," from Mid.Pers. panj; Av. panca; cf. Skt. pánca; Gk. pente; L. quinque; O.E. fif, from P.Gmc. *fimfe (O.S. fif, O.H.G. funf); from PIE base *penk^we "five."

An → aberration of a → lens  → system in which → magnification increases with → distance from the → optical axis, whereby → horizontal and → vertical lines bend inward toward the → center of the → field. Opposite of → barrel distortion.

Pincushion, from pin, from M.E. pinne, O.E. pinn "peg;" cf. D. pin, Ger. Pinne; perhaps from L. pinna "feather, quill" + cushion, M.E. cuisshin, O.Fr. coissin (Fr. coussin) a variant of V.L. *coxinum, either from L. coxa "hip, thigh," or from L. culcita "mattress;" → distortion.

Cowlegi, → distortion; bâleštaki, adj. of bâleštak, diminutive of bâlešt, variant bâleš "cushion, pillow," Mid.Pers. bâlišn, bâlên "cushion, pillow;" Av. barəiš- "pillow, cushion;" cf. Skt. barhis- "straw, a bed or layer of kusa grass strewed over the sacrificial ground."

In a → planispheric astrolabe, a vane on an end of an → alidade with a hole, slot, or other indicator through which one can view a distant object. There may also be a pointer or pointers on the alidade to indicate a position on a scale.

Diminutive of L. pinna "feather, wing, fin;" + → -ule.

Mori (Biruni).

A child's toy consisting of a wheel or leaflike curls of paper or plastic loosely attached by a pin to a stick, designed to revolve when blown by or as by the wind (Dictionary.com).

→ pin; → wheel.

Ferferé "pinwheel," of unknown origin.

An unstable nuclear particle of mass intermediate between that of a proton and an electron; also called π meson.

From pi (meson) + → -on.

1) A long tube of metal, plastic, etc, used to conduct water, oil, gas, etc.
2) A device consisting of a tube used for smoking.

M.E., O.E. pipe "musical wind instrument; tube," from V.L. *pipa "a pipe," from L. pipare "to chirp, to peep," of imitative origin (cf. It. pipa, Fr. pipe, Ger. Pfeife, Du. pijp).

1) Lulé, → tube.
2) Pip loan from Fr., as above.

An extended complex of → molecular clouds in the constellation → Ophiuchus, apparently shaped like a smoker's pipe, about 5° in size and located about 5° away from the → Galactic center. It has a mass of 10⁴ solar masses, lies at a distance of about 130 pc, and is among the closest molecular clouds to Earth. The Pipe Nebula includes a number of → dark nebulae, including Barnard 59, 65, 66, 67, 77, 244, and 256. It is of particular interest because of the almost complete lack of → star formation within it. This cloud is an extremely rare example of a relatively massive molecular cloud that may be in a state of evolution prior to the onset of significant star-forming activity.

→ pipe; → nebula.

1) A long tubular conduit or series of pipes used to transport crude oil, natural gas, water, etc., often underground and over great distances.
2) A channel or process along which something passes or is provided at a steady rate.

→ pipe; → line.

The Fishes. An extensive but faint constellation of the → Zodiac, representing a pair of fishes, located in the northern hemisphere, at 1h right ascension, 15° north declination. Abbreviation: Psc; genitive: Piscium.

L., plural of piscis "fish," cognate with Goth. fisks, O.E. fisc.

Mâhi "fish," from Mid.Pers. mâhik; Av. masya-; cf. Skt. matsya-, Pali maccha-.

The Southern Fish. A small constellation in the southern hemisphere, at 22h 30m right ascension, 30° south declination. Its brightest star, → Fomalhaut, has apparent visual magnitude 1.3. Abbreviation: PsA; genitive: Piscis Austrini.

L. piscis "fish," cognate with Goth. fisks, O.E. fisc; austrinus "southern."

Mâhi "fish," → Pisces; daštari "southern," → south.

A disk or cylindrical part tightly fitting and moving within a cylinder, either to compress or move a fluid collected in the cylinder, as air or water, or to transform energy imparted by a fluid entering or expanding inside the cylinder, as compressed air, explosive gases, or steam, into a rectilinear motion usually transformed into rotary motion by means of a connecting rod (Dictionary.com).

From Fr. piston, from M.Fr. piston "large pestle," from O.It. pistone "a piston," from pestare "to pound," from L.L. pistare, from pistare "to pound."

The sensation of a sound frequency; the relative highness or lowness that we hear in a sound. A high pitch sound corresponds to a high frequency sound wave and a low pitch sound corresponds to a low frequency sound wave. In music, a sound that has a definite pitch is called a → tone. Sounds may be generally characterized by pitch, → loudness, and → quality.

M.E. picchen "to thrust, pierce, set;" maybe akin to pick.

Dong "voice, sound," variants bâng, vâng, vang, zang, Tabari šong "cry;" related to vâž, → word.

A natural ore consisting mainly of → uranium oxide, U₃O₈, with small amounts of → radium, of which is the principal source. It usually contains some → lead and variable amounts of → thorium and → rare-earth elements.

From Ger. Pechblende, from Pech "pitch" (from its black color) + Blende "a mineral."

A → device used to → measure the → velocity of a flowing → fluid. The Pitot tube is used on → aircrafts to determine their → speed. It is also used to meaure water speed of a boat as well as liquid, air, and gas velocities in industrial applications. It is a small tube that has two holes on it. The front hole is placed in the airstream to measure the → stagnation pressure. The side hole measures the → static pressure. The difference between these pressures gives the → dynamic pressure, which can be used to calculate airspeed. See also the → Bernoulli equation.

Named after the French inventor Henri Pitot (1695-1771), a hyraulic engineer; → tube.