1. (n.) Friendly intercourse; reciprocal exchange of civilities; especially, intercourse between persons by means of letters.

2. (n.) The letters which pass between correspondents.

3. (n.) Mutual adaptation, relation, or agreement, of one thing to another; agreement; congruity; fitness; relation.

ESP PP RD RFD accommodation accompaniment accord accordance account acquiescence adaptation adaption adjustment affinity agape agreement airmail alikeness alliance amity analogy annals answer aping approach approximation assent assimilation association balance bilateral symmetry bonds of harmony book post brotherly love cahoots calm caritas catalog cement of friendship charity chorus chronicle closeness co-working coaction coequality coextension coherence coincidence collaboration collectivity collusion combination combined effort commerce communication communion community community of interests comparability comparison compatibility compliance concert concerted action concomitance concord concordance concourse concurrence confluence conformance conformation conformation other-direction conformity congeniality congress congruence congruency congruity conjunction connection consilience consistency consonance consort conspiracy constancy contact continuity conventionality conversation converse cooperation copying corelation correlation correlativism correlativity dealing dealings direct mail direct-mail selling documentation dynamic symmetry empathy equability equality equanimity equation equilibrium equipoise equipollence equiponderance equity equivalence equivalency esprit esprit de corps eurythmics eurythmy evenness exchange express feeling of identity fellow feeling fellowship finish flexibility fourth-class mail frank frictionlessness good vibes good vibrations halfpenny post happy family harmony history homogeneity homoousia identity imitation indistinguishability information interaction interchange intercommunication intercommunion intercourse interplay intersection inventory inverse proportion inverse ratio inverse relationship junction junk mail justice keeping kinship letter post letters levelness like-mindedness likeness likening line linguistic intercourse list love mail mail-order selling mailing list malleability memorial message mimicking monolithism multilateral symmetry mutuality nearness newspaper post no difference obedience observance oneness orthodoxy overlap par parallelism parasitism parcel post parity peace persistence pipe roll pliancy poise polarity post post day proportion proportionality rapport rapprochement reciprocality reciprocation reciprocity reconcilement reconciliation record recording register registered mail registry regularity relativity relic remains reply resemblance response roll rolls roster rota rural delivery rural free delivery sameness saprophytism scroll sea mail seapost self-consistency self-identity selfhood selfness selfsameness semblance shapeliness sharing similarity simile similitude simulation simultaneity social intercourse solidarity speaking special delivery special handling speech speech circuit speech situation