cordial adj.

"of or pertaining to the heart," c. 1600, from French cardiaque (14c.) or directly from Latin cardiacus, from Greek kardiakos "pertaining to the heart," from kardia "heart" (from PIE root *kerd- "heart"). Cardiac arrest is attested from 1950.

Greek kardia also could mean "stomach" and Latin cardiacus "pertaining to the stomach." This terminology continues somewhat in modern medicine. Confusion of heart and nearby digestive organs also is reflected in Breton kalon "heart," from Old French cauldun "bowels," and English heartburn for "indigestion."

Proto-Indo-European root meaning "heart."

It forms all or part of: accord; cardiac; cardio-; concord; core; cordial; courage; credence; credible; credit; credo; credulous; creed; discord; grant; heart; incroyable; megalocardia; miscreant; myocardium; pericarditis; pericardium; quarry (n.1) "what is hunted;" record; recreant; tachycardia.

It is the hypothetical source of/evidence for its existence is provided by: Greek kardia, Latin cor, Armenian sirt, Old Irish cride, Welsh craidd, Hittite kir, Lithuanian širdis, Russian serdce, Old English heorte, German Herz, Gothic hairto, "heart;" Breton kreiz "middle;" Old Church Slavonic sreda "middle."

late 15c., "by heart" (Caxton), from cordial + -ly (2). Meaning "heartily, earnestly" is from 1530s; weakened sense of "with friendliness" is attested by 1781.