late 15c., "consanguinity, blood-relation," a sense now obsolete; see sanguine + -ity. Meaning "quality or character of being sanguine" is by 1737. 

1520s, "to recount, tell," from French relater "refer, report" (14c.) and directly from Latin relatus, used as past participle of referre "bring back, bear back" (see refer), from re- "back, again" + lātus "borne, carried" (see oblate (n.)).

The meaning "stand in some relation; have reference or respect" is from 1640s; transitive sense of "bring (something) into relation with (something else)" is from 1690s. Meaning "to establish a relation between" is from 1771. Sense of "to feel connected or sympathetic to" is attested from 1950, originally in psychology jargon. Related: Related; relating.

"a habitual living on or at the expense of another," 1610s, from parasite + -ism. Biological sense of "vital relation of a parasite to a host" is by 1840.

also electro-magnetism, "the collective term for phenomena which rest upon the relation between electric currents and magnetism," 1821; see electro- + magnetism.

late 14c., mornere, "one who laments or grieves" (especially for the death of a friend or relation), agent noun from mourn (v.). Meaning "one hired to lament for the dead" is from 1690s.

"the secondary term of a relation, that to which something is related," 1640s, perhaps a back-formation from correlation or from correlate (adj.), from a Medieval Latin adjectival use of the Latin past participle.

linking or connecting verb (especially "be"), word which expresses relation between subject and predicate, 1640s, from Latin copula "that which binds, rope, band, bond" (see copulate). Related: Copular.

before vowels chem-, word-forming element denoting "relation to chemical action or chemicals," from combining form of chemical (adj.), used to form scientific compound words from c. 1900. In 19c., chemico- was used.

1670s, "to assume a position" (intransitive), from position (n.). Transitive sense of "place or put in relation to other objects," now the usual meaning, is recorded from 1817. Related: Positioned; positioning.