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

An object's celestial position as determined for a given mean equator and equinox. → mean position.

→ mean; → place.

The direction of the Earth's axis at a particular epoch if the nutation is ignored.

→ mean; → pole.

Same as → mean place.

→ mean; → position.

The shape of a pulsar's pulse as determined by averaging several pulses.

→ mean; → profile.

The average time interval between two successive → upper transits of the → mean equinox.

→ mean; → sidereal; → day.

The hour angle of the mean equinox for a given observer.

→ mean; → sidereal; → time.

The average length of the apparent solar day. In other words, the interval between successive transits of the mean Sun for a given observer.

→ mean; → solar; → day.

The time since the mean Sun crossed the meridian with 12 hours added to make the day begin at midnight.

→ mean; → solar; → time.

A plot of the mass-to-charge ratio of elementary particles, sorted by their isotopic mass.

→ mean; → spectrum.

A hypothetical Sun that moves along the ecliptic at a uniform rate equal to the average motion of the real Sun.

→ mean; → sun.

In → syllogism, the term which is common to both → premises and is excluded from the → conclusion.

→ mean; → term.

1) If f(x) is a continuous function on the interval from a to b, then:
∫ f(x) dx = f(c)(b - a) (summed from a to b) for at least one point in that interval.
2) More generally, If f(x) and g(x) are continuous functions on the interval from a to b and g(x)≥ 0, then:
∫ f(x)g(x) dx = f(c) ∫ g(x) dx (both integrals summed from a to b).

→ mean; → value; → theorem.

The sense or significance of a word, sentence, symbol, etc. The study dealing with meanings is called → semantics. See also → semiotics.

M.E., from mean; O.E. mænan "to mean, intend, signify" (cf. O.Fris. mena "to signify," O.S. menian "to intend, signify," M.Du. menen, Du. meenen, Ger. meinen "think, suppose"), related to Pers. maneš "disposition, temperament," mênidan "to think, consider," → idea; + → -ing.

Cemâr, from cem or cim "meaning, signification;" Mid.Pers. cim "meaning, reason, cause;" ultimately from Proto-Ir. *cahmāt "wherefore?" cf. Skt. kasmāt "why, where from? whence?," kim "what? how? why?" + âr short form of âvar present stem of âvardan "to cause or produce; to bring," → production, as in bonâr, → cause, used also as a nuance suffix; see also the verb → mean.

1) A unit or standard of → measurement; the act or process of ascertaining the extent, dimensions, or quantity of something; measurement; the quantity obtained by such a process.
2) To use standard units to determine the magnitude, extent, size, etc. of something. The quantity obtained by such a process.

From O.Fr. mesurer, from L.L. mensurare "to measure," from L. mensura "a measuring, a thing to measure by," from mensus, p.p. of metiri "to measure," → meter.

1) Andâzé "measure," from Mid.Pers. andâzag, handâcak "measure," handâxtan, handâz- "to measure," Manichean Mid.Pers. hnds- "to measure," Proto-Iranian *hamdas-, from ham-, → com-, + *das- "to heap, amass;" cf. Ossetic dasun/dast "to heap up;" Arm. loanword dasel "to arrange (a crowd, people)," das "order, arrangement."
2) Andâzé gereftan, compound verb, literally "to take measure," from andâzé, as above, + gereftan "to take, seize" (Mid.Pers. griftan; Av./O.Pers. grab- "to take, seize;" cf. Skt. grah-, grabh- "to seize, take," graha "seizing, holding, perceiving;" M.L.G. grabben "to grab;" from P.Gmc. *grab; E. grab "to take or grasp suddenly;" PIE base *ghrebh- "to seize").

1) The act of measuring; a measured quantity.
2) The determination of the magnitude or amount of a quantity by comparison (direct or indirect) with the prototype standards of the system of units employed (IEEE Standard Dictionary of Electrical and Electronics Terms). → absolute measurement, → measurement uncertainty, → Roemer's measurement.

Verbal noun of → measure.

The interval within which lies the actually measured value of a physical quantity and the true value of the same physical quantity.

→ measurement; uncertainty, from negation prefix un- + → certainty.

A person who repairs and maintains machinery, motors, etc. (Dictionary.com). Same as → mechanician.

→ mechanics.

1) Of, connected with, produced by → mechanics.
2) Like machines; automatic.

→ mechanic; → -al.

The energy that is possessed by an object due to its motion or due to its position. It is equal to the sum of the → kinetic energy and → potential energy.

→ mechanical; → energy.

1) The state of a → rigid body if, as viewed from an → inertial frame of rest: 1) the → linear acceleration of its → center of mass is zero, and 2) its → angular acceleration about any axis fixed in this reference frame is zero. The center of mass may be moving with constant velocity and the body may be rotating about a fixed axis with constant angular velocity.
2) In → thermodynamics, the state of a system in which → pressure is the same every where with no other forces acting on the system except a uniform external pressure.

→ mechanical; → equilibrium.