different between reciprocal vs diopter

English

Etymology

Latin reciprocus, possibly from a phrase such as reque proque (“back and forth, to and fro”), from re- (“back”), pr? (“forwards”) and -que (“and”).

Pronunciation

• IPA^(key): /???s?p??k(?)l/

Adjective

reciprocal (not comparable)

1. Of a feeling, action or such: mutual, uniformly felt or done by each party towards the other or others; two-way.
2. Mutually interchangeable.
   • 1725, Isaac Watts, Logick, or The Right Use of Reason in the Enquiry After Truth With a Variety of Rules to Guard

     These two rules will render a definition reciprocal with the thing defined.

3. (grammar) expressing mutual action, applied to pronouns and verbs; also in a broad sense: reflexive
4. (mathematics) Used to denote different kinds of mutual relation; often with reference to the substitution of reciprocals for given quantities.
5. Done, given, felt, or owed in return

Synonyms

• mutual, two-way
• contrary, opposite, converse, inverse, inverted, cross
• (grammar): reflexive
• See also Thesaurus:contrary

Derived terms

• irreciprocal

Related terms

• reciprocity

Translations

Noun

reciprocal (plural reciprocals)

1. (arithmetic) The number obtained by dividing 1 by another given number; the result of exchanging the numerator and the denominator of a fraction.

2. (grammar) A construction expressing mutual action.
   • 2008, Ekkehard König, Volker Gast, Reciprocals and Reflexives: Theoretical and Typological Explorations

     Depending on where reciprocalization applies (syntax vs. lexicon), the relevant reciprocal verbs are claimed to exhibit specific properties, in particular: (i) syntactic reciprocals are fully productive whereas lexical reciprocals have only limited productivity; […]

Synonyms

• (in arithmetic): multiplicative inverse

Translations

English

Alternative forms

• dioptra
• dioptre
• dioptry (obsolete)

Etymology

From Latin dioptra, from Ancient Greek ??????? (dióptra).(Can this⁽⁺⁾ etymology be sourced?)

Noun

diopter (plural diopters)

1. A unit of measure of the power of a lens or mirror, equal to the reciprocal of its focal length in meters. Myopia is diagnosed and measured in diopters.
2. The dioptre adjustment mechanism of a pair of binoculars or of a camera viewfinder.
3. (photography, dated) A lens element attached to the front of a photographic lens to shorten the lens's minimum focus distance; also called a "close-up filter".
4. (obsolete) Any lens system, such as a telescope.
5. (obsolete) A theodolite or similar surveyor’s angle measuring device.
6. (obsolete) An alidade.
7. (obsolete) A surgical speculum.
8. (obsolete) An instrument for drawing the skull by projections.

Translations

References

Anagrams

• dioptre, peridot, periodt, proetid, proteid, protide, pterido-, pteroid, reptoid