reciprocal

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

• IPA^(key): /ɹɪˈsɪpɹək(ə)l/

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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.

   Synonym: reciprocating

   reciprocal love

   reciprocal duties

   • c. 1603–1606, William Shakespeare, “The Tragedie of King Lear”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, →OCLC, [Act IV, scene vi], page 304, column 2:

     Let our reciprocall vowes be remembred.

2. Mutually interchangeable.
   • 1725, Isaac Watts, Logick: Or, The Right Use of Reason in the Enquiry after Truth, […], 2nd edition, London: […] John Clark and Richard Hett, […], Emanuel Matthews, […], and Richard Ford, […], published 1726, →OCLC:

     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.

   a reciprocal invitation to lunch

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

• reciprocity

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.

   Synonym: multiplicative inverse

   0.5 is the reciprocal of 2.

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; […]