The Collaborative International Dictionary of English v.0.48:

Relation \Re*la"tion\ (r?-l?"sh?n), n. [F. relation, L. relatio.
   See Relate.]
   1. The act of relating or telling; also, that which is
      related; recital; account; narration; narrative; as, the
      relation of historical events.
      [1913 Webster]

            ??????oet's relation doth well figure them. --Bacon.
      [1913 Webster]

   2. The state of being related or of referring; what is
      apprehended as appertaining to a being or quality, by
      considering it in its bearing upon something else;
      relative quality or condition; the being such and such
      with regard or respect to some other thing; connection;
      as, the relation of experience to knowledge; the relation
      of master to servant.
      [1913 Webster]

            Any sort of connection which is perceived or
            imagined between two or more things, or any
            comparison which is made by the mind, is a relation.
                                                  --I. Taylor.
      [1913 Webster]

   3. Reference; respect; regard.
      [1913 Webster]

            I have been importuned to make some observations on
            this art in relation to its agreement with poetry.
                                                  --Dryden.
      [1913 Webster]

   4. Connection by consanguinity or affinity; kinship;
      relationship; as, the relation of parents and children.
      [1913 Webster]

            Relations dear, and all the charities
            Of father, son, and brother, first were known.
                                                  --Milton.
      [1913 Webster]

   5. A person connected by cosanguinity or affinity; a
      relative; a kinsman or kinswoman.
      [1913 Webster]

            For me . . . my relation does not care a rush. --Ld.
                                                  Lytton.
      [1913 Webster]

   6. (Law)
      (a) The carrying back, and giving effect or operation to,
          an act or proceeding frrom some previous date or time,
          by a sort of fiction, as if it had happened or begun
          at that time. In such case the act is said to take
          effect by relation.
      (b) The act of a relator at whose instance a suit is
          begun. --Wharton. Burrill.
          [1913 Webster]

   Syn: Recital; rehearsal; narration; account; narrative; tale;
        detail; description; kindred; kinship; consanguinity;
        affinity; kinsman; kinswoman.
        [1913 Webster]

WordNet (r) 3.0 (2006):

relation
    n 1: an abstraction belonging to or characteristic of two
         entities or parts together
    2: the act of sexual procreation between a man and a woman; the
       man's penis is inserted into the woman's vagina and excited
       until orgasm and ejaculation occur [syn: sexual
       intercourse, intercourse, sex act, copulation,
       coitus, coition, sexual congress, congress, sexual
       relation, relation, carnal knowledge]
    3: a person related by blood or marriage; "police are searching
       for relatives of the deceased"; "he has distant relations
       back in New Jersey" [syn: relative, relation]
    4: an act of narration; "he was the hero according to his own
       relation"; "his endless recounting of the incident eventually
       became unbearable" [syn: relation, telling, recounting]
    5: (law) the principle that an act done at a later time is
       deemed by law to have occurred at an earlier time; "his
       attorney argued for the relation back of the amended
       complaint to the time the initial complaint was filed" [syn:
       relation back, relation]
    6: (usually plural) mutual dealings or connections among persons
       or groups; "international relations"

Moby Thesaurus II by Grady Ward, 1.0:

193 Moby Thesaurus words for "relation":
   about, absorption, affective meaning, affiliation, agnation,
   allegory, alliance, analogy, ancestry, anent, apropos, association,
   associations, balancing, bearing, blood, blood relationship,
   blood relative, brotherhood, brothership, capacity,
   carnal knowledge, character, cognation, coitus, coloring,
   common ancestry, common descent, comparative anatomy,
   comparative degree, comparative grammar, comparative judgment,
   comparative linguistics, comparative literature,
   comparative method, compare, comparing, comparison, concerning,
   condition, confrontation, confrontment, connection, connotation,
   consanguinity, consequence, contrast, contrastiveness, correlation,
   correspondence, cousinhood, cousinship, criminal conversation,
   dealings, delineation, denotation, description, distinction,
   distinctiveness, doings, drift, effect, embarrassment, enation,
   engagement, enmeshment, entanglement, essence, extension,
   fatherhood, filiation, force, fraternity, gist,
   grammatical meaning, idea, impact, implication, import,
   in relation to, inclusion, intension, interconnection, intercourse,
   interdependence, involution, involvement, kin, kindred, kinship,
   kinsman, kinswoman, lexical meaning, liaison, likening, link,
   links, literal meaning, matching, maternity, matrilineage,
   matriliny, matrisib, matrocliny, meaning, metaphor, motherhood,
   narration, narrative, opposing, opposition, overtone, parallelism,
   part, paternity, patrilineage, patriliny, patrisib, patrocliny,
   pertaining to, pertinence, pith, point, portrayal, position,
   practical consequence, propinquity, proportion, purport, quality,
   range of meaning, re, real meaning, recapitulation, recital,
   recitation, recountal, recounting, reference, referent,
   referring to, regarding, rehearsal, relations, relationship,
   relative, relevance, report, respecting, retelling, review, role,
   scope, semantic cluster, semantic field, sense, sex,
   sexual intercourse, sibship, significance, signification,
   significatum, signifie, simile, similitude, sisterhood, sistership,
   span of meaning, spirit, status, story, structural meaning,
   substance, sum, sum and substance, symbolic meaning, tale-telling,
   telling, tenor, tie, tie-in, ties of blood,
   totality of associations, transferred meaning, trope of comparison,
   truck, unadorned meaning, undertone, value, weighing,
   with regard to, with respect to, yarn spinning



The Free On-line Dictionary of Computing (30 December 2018):

relation

   1.  A subset of the product of two sets, R : A
   x B.  If (a, b) is an element of R then we write a R b,
   meaning a is related to b by R.  A relation may be:
   reflexive (a R a), symmetric (a R b => b R a),
   transitive (a R b & b R c => a R c), antisymmetric (a R b
   & b R a => a = b) or total (a R b or b R a).

   See equivalence relation, partial ordering, pre-order,
   total ordering.

   2.  A table in a relational database.

   (1995-02-28)


Bouvier's Law Dictionary, Revised 6th Ed (1856):

RELATION, civil law. The report which the judges made of the proceedings in
certain suits to the prince were so called.
     2. These relations took place when the judge had no law to direct him,
or when the laws were susceptible of difficulties; it was then referred to
the prince, who was the author of the law, to give the interpretation. Those
reports were made in writing and contained the pleadings of the parties, and
all the proceedings, together with the judge's opinion, and prayed the
emperor to order what should be done. The ordinance of the prince thus
required was called a rescript. (q.v.) the use of these relations was
abolished by Justinian, Nov. 125.



Bouvier's Law Dictionary, Revised 6th Ed (1856):

RELATION, contracts, construction. When an act is done at one time, and it
operates upon the thing as if done at another time, it is said to do so by
relation; as, if a man deliver a deed as an escrow, to be delivered by the
party holding it, to the grantor, on the performance of some act, the
delivery to the latter will have relation back to the first delivery. Termes
de la Ley. Again, if a partner be adjudged a bankrupt, the partnership is
dissolved, and such dissolution relates back to the time when the commission
issued. 3 Kent, Com. 33. Vide 18 Vin. Ab. 285; 4 Com. Dig. 245; 5 Id. 339;
Litt. S. C. 462-466; 2 John. 510; 4 John. 230; 15 John. 809; 2 Har. & John.
151, and the article Fiction.