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

A suffix used to form abstract nouns expressing state, degree, or condition: metallicity, luminosity, periodicity, Gaussianity.

From M.E. -ite, from O.Fr. -ité, from L. -itas (-itat-), from -i- (thematic or, rarely, connective vowel) + -tas (-tat-), may be cognate with Av./Skt. -tāt (as in Av. uparatāt, Skt. uparátāt "supremacy," Av. ha^urvatāt, Skt. sarvátāt "completeness").

The suffix -igi, from -ig adj. suffix, variant of -ik, → -ic, + -i noun suffix.

Note: The Pers. suffix -i forms state/condition nouns from adjectives, as in: xubi, zešti, râsti, âzâdi, tanhâyi. There is though a phonetic problem when the adj. ends in -i, since two successive i's are not easily articulable, e.g.: felez "metal," felezi "metallic," *felezii "metallicity." Mid.Pers. did not have this problem, since the adj. suffix was -îg or -îk (instead of -i) and the noun suffix -îh (instead of -i). Some examples in Mid.Pers.: tuhîg "empty," tuhîgîh "emptiness," tuwânîg "able," tuwânîgîh "ability," spurrîg "complete," spurrîgîh "completeness, perfection," nazdîk "near," nazdîkîh "proximity." A way out of this phonetic problem is to use the Mid.Pers. -igi. This solution, first introduced in the case of tohi, tohigi (→ void), was generalized by M. Sch. Adib-Soltâni (Irânigi, Âlmânigi, darunâxtigi, borunâxtigi, etc.). This seems a natural solution since the adj. suffix -i is the evolution of the Mid.Pers. -ig, and moreover Pers. currently revives the g phoneme in comparable phonetic situations, as in the ending phoneme -é (-eh), which derives from Mid.Pers. -ag. A number of examples: adj. âzâdé, n. âzâdegi; adj. tâbandé, n. tâbandegi; adj. mardâné, n. mardânegi; likewise xâné, xânegi, setâré, setâregân; âzâdé, âzâdegân. Interestingly, the -igi suffix has this specified function in some dialects, for example (Tajik, Šahrezâ-yi) xâligi "emptiness," from xâli.
Some examples for the use of -igi in this work: felezigi, → metallicity; mâddigi, → materiality; beyzigi, → ellipcity, tâštigi, → certainty, etc.

In a system of moist air, the ratio of the mass of water vapor to the total volume of the system. → humidity.

→ absolute; → humidity.

A star's → intrinsic brightness, i.e. the total amount of energy radiated by the star per second. → Luminosity is often expressed in units of watts or erg/sec. The Sun's absolute luminosity is 3.86 × 10³³ erg/sec.

→ absolute; → luminosity.

→ magnetic permeability.

→ absolute; → permeability.

Same as → viscosity and → dynamic viscosity.

→ absolute; → viscosity.

The ratio of energy absorbed by a body to energy incident upon the same body.

Absorptivity, from absorptive adj. from → absorb + → -ity, suffix expressing state or condition.

Daršamâyi, from daršamâ quality adj. from daršam, present stem of daršamidan + -yi noun suffix.

For a spatial object, the ratio between its absorption of solar radiation and its infrared emission.

→ absorptivity; → emissivity; → ratio.

The quality or state of being absurd; something that is absurd.

→ absurd + → -ity.

The acceleration that an object experiences because of gravity when it falls freely close to the surface of a massive body, such as a planet. Same as → gravitational acceleration.

→ acceleration; → gravity.

For a radioactive substance, the average number of atoms disintegrating per unit time.

Activity, from → active + -ity.

Žirandegi, noun from žirandé, → active.

1) The quality or state of being actual or something that is actual; reality.
2) Philosophy: According to Aristotle, what has → form and can causally interact with other things, as opposed to → potentiality.

→ actual; → -ity.

Sharpness; acuteness; keenness of perception.

M.E., from M.Fr. acuité, from M.L. acuitatem (nom. acuitas) "sharpness," from L. acus "needle," acuere "to sharpen," from PIE root *ak- "be sharp."

Tiznâ "sharpness," from tiz, "→ sharp," + -nâ, a suffix that transforms adjective into noun (compare with tangnâ, derâznâ, farâxnâ, etc.).

The ability of the → eye to see separately two points close to each other. It is a measure of the → resolving power of the eye's → optical system and depends on the density of cells in the → retina. The maximum acuity of the normal human eye is around 0.5 minutes of arc.

→ acuity; → vision.

The number which can be added to any other number without changing the magnitude of that number: zero. → multiplicative identity.

→ additive; → identity.

If E₁, E₂, ..., E_n are n → mutually exclusive events, then the probability of occurrence of at least one of them is the sum of their individual probabilities: P(E₁ + E₂ + ... + E_n) = P(E₁) + P(E₂) + ... + P(E_n).

→ additive; → law; → probability.

1) General: A relationship or resemblance.
2) Math.: The state, quality, or fact of being → affine.

→ affine; → -ity.

same as → Alfven speed.

→ Alfven wave; → velocity.

→ Alfvénic fluctuation.

→ Alfvénic; → -ity.

→ Alfvénic fluctuation.

→ Alfvénic; → -ity.

The quality of state of being → ambiguous.

→ ambiguous; → -ity.