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

The convention for measuring angles on the sky in astronomy (Abbreviated as PA). It is the direction of an imaginary arrow in the sky, measured from north through east: 0° = north, 90° = east, 180° = south, and so on to 359° and back to 0°. Applied to a binary system it is the direction of a secondary body or feature from a primary, measured in the system. .

→ position; → angle.

In single dish astronomy, an observing mode in which the telescope is moved between the object position and a user defined reference position. The aim is to eliminate unwanted signals in the baseline. → beam switching; → frequency switching.

→ position; → switching.

Relating to or determined by position.

→ position; → -al.

The branch of astronomy that is used to determine the location of objects on the celestial sphere, as seen at a particular date, time, and location on the Earth. Same as → spherical astronomy.

→ positional; → astronomy.

A system of representing → numbers in which the → position of a → digit in a string of digits affects its value. The decimal system is a positional notation for expressing numbers. Same as → place-value notation and → positional number system.

→ positional; → notation.

A → number system in which the value of each digit is determined by which place it appears in the full number. The lowest place value is the rightmost position, and each successive position to the left has a higher place value. In the → number system conversion, the rightmost position represents the "ones" column, the next position represents the "tens" column, the next position represents "hundreds", etc. The values of each position correspond to powers of the → base of the number system. For example, in the usual decimal number system, which uses base 10, the place values correspond to powers of 10. Same as → place-value notation and → positional notation. See also → number system conversion.

→ positional; → number; → system.

The act or process of putting in a particular position or determining the psition of.

Verbal noun of → position; → -ing.

1) General: Explicitly stated, stipulated, or expressed.
2) Capable of being measured, detected, or perceived.
3) Math.: Noting a quantity greater than zero.
4) Physics: Having an electrical charge of the same polarity as that of a proton.
5) Photography: Having colors or values of dark and light corresponding to the subject.
6) Philosophy: Relating to the theory that knowledge can be acquired only through direct observation and experimentation, and not through metaphysics or theology. → positivism.
7) Law: Conclusive and beyond doubt or question; irrefutable.
8) Opposite of → negative.
See also:
→ positive charge, → positive correlation, → positive feedback, → positive skewness, → positiveness, → positivism.

M.E., from O.Fr. positif, from L. positivus "placed, settled; positive" (opposed to naturalis "natural"), from posit-, from positus "placed, put," p.p. of ponere "to put, place, set" + -ivus a suffix of adjectives.

Dâhidâr, from dâhid- + -âr. The first component is the past stem of *dâhidan "to put, create, determine," variant of dehidan, dâdan "to give;" from Mid.Pers. dâdan, dahidan "to give; to create;" O.Pers. dā- "to give, grant, yield;" Av. dā- "to give, grant; put; create; determine;" dāhi "he would give/put" (single second person, subjunctive transitive), dadāiti "he gives;" cf. Skt. dadáti "he gives;" Gk. tithenai "to place, put, set," didomi "I give;" L. dare "to give, offer," facere "to do, to make;" Rus. delat' "to do;" O.H.G. tuon, Ger. tun, O.E. don "to do;" PIE base *dhe- "to put, to do." The second component -âr, accusative suffix; on the model of gereftâr "captive, involved (in trouble)," didâr "exposed to view."

A charge having sign opposite to that of the electron.

→ positive; → charge.

Same as → direct correlation.

→ positive; → correlation.

A → feedback process in which the → output reacts on the → input so as to increase the initial → effect.

→ positive; → feedback.

Of a distribution function, a skewness in which the right tail (tail at the large end of the distribution) is more pronounced than the left tail (tail at small end of the distribution). → negative skewness.

→ positive; → skewness.

The quality or state of being positive; positivity.

→ positive + → -ity.

Any doctrine that excludes a priori affirmations and admits only positive truth, i.e. factual knowledge gained through observation.

From Fr. positivisme, from positif, → positive, in its philosophical sense of "imposed on the mind by experience;" → -ism.

The → antiparticle of the → electron, which has the same → mass, → spin, and → electric charge as the electron, but the charge is → positive. Positrons may be generated by → radioactive decay or by → pair production from energetic → gamma ray photons.

From posi(tive), → positive + (elec)tron→ electron.

A short-lived bound state of a positron and an electron.

From → positron + -ium (as in barium, titanium), from N.L., from L. neuter suffix.

1) To have as belonging to one; have as property; own.
2) To have as a faculty, quality, or the like.
3) Of a spirit, especially an evil one) to occupy, dominate, or control (a person) from within (Dictionary.com).

M.E. possesen, from M.Fr. possesser, "to have and hold, take, be in possession of," from L. possess-, p.p. stem of possidere "to have and hold, be master of, own," probably a compound of potis "having power, powerful, able," from PIE root *poti- "powerful; lord;" from which also derived Skt. patih "master, husband," Gk. posis, Lithuanian patis "husband" + sedere, from PIE root *sed-, "to → sit."

Dâreštidan, infinitive and back formation from dârešt, → possession.

1) The act or fact of possessing; the state of being possessed.
2) A thing possessed (Dictionary.com).

→ possess; → -tion.

Dârešt, verbal noun of dâštan "to have, possess" (on the model of konešt, from kardan; xoršt, from xordan; bâlešt, from bâlidan; râmešt, from râmidan; (Lori) zenešt, from zadan; (Nowdân, Fârs) perešt, from paridan); Mid.Pers. dâr-, dâštan "to have, hold, preserve;" O.Pers./Av. dar- "to hold, keep back, maintain, keep in mind;" Skt. dhr- "to hold, keep, preserve," dharma- "what is established or firm; law;" Gk. thronos "elevated seat, throne," L. firmus "firm, stable," Lith. daryti "to make," PIE *d^her- "to hold, support."

1) Of or relating to possession or ownership.
2) having or showing an excessive desire to possess, control, or dominate.
3) Denoting an inflected form of a noun or pronoun used to convey the idea of possession, association, etc.; the possessive case (Dictionary.com).

→ possess; → -tion.

Same as → genitive case.

→ possessive; → case.