# An Etymological Dictionary of Astronomy and AstrophysicsEnglish-French-Persian

## فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

### M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 5 Search : modulus
 distance modulus   پیمون ِ اپست   peymun-e apestFr.: module de distance   The difference between the → apparent magnitude (m) of a star or galaxy and its → absolute magnitude (M). It is given by m - M = 5 log d - 5, where d is the distance in → parsecs. For an object that is 10 pc away, the distance modulus is zero.→ distance; → modulus. modulus   پیمون   peymunFr.: module   A real, positive quantity that measures the magnitude of some number. For instance, the modulus of a complex number is the square root of the sum of the squares of its components. Often it means, simply, the numerical ("absolute") value of an algebraic quantity.From L. modulus, → module.Peymun, variant of peymâné "a measure either for dry or wet goods; a bushel, cup, bowl," from peymudan, peymâyidan "to measure," from Mid.Pers. patmudan, paymudan "to measure (against)," from *pati-māya-. The first element *pati- "against, back" (cf. Mod.Pers. pâd- "agaist, contrary to;" Mid.Pers. pât-; O.Pers. paity "agaist, 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). The second element from *mā- "to measure;" O.Pers./Av. mā(y)- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure." Apart from peymâné, several other terms in Mod.Pers. are related to this second element, which occurs also as mun, mân, man, mâ, mu, and mây: pirâmun "perimeter," âzmun, âzmây- "test, trial," peymân "measuring, agreement," man "a measure weighing forty seers"), nemudan, nemâ- "to show, display," âmâdan, âmây- "to prepare." modulus of rigidity   پیمون ِ سخت‌پایی   peymun-e saxtpâyiFr.: module de rigidité   Same as → shear modulus.→ modulus; → rigidity. shear modulus   پیمون ِ کرن   peymun-e karnFr.: module de cisaillement   The ratio of the applied → stress to the change in shape (→ strain) produced in an → elastic body. The bigger this quantity the more rigid is the material since for the same change in strain a bigger force is needed. Also called → shear modulus.→ shear; → modulus. Young's modulus   پیمون ِ یانگ   peymun-e YoungFr.: module de Young   A measure of elasticity of a material, defined as the ratio of tensile → stress to tensile → strain, which equals the ratio of compressive stress to compressive strain.Named after Thomas Young, → Young's experiment.