"muscular substance of the heart," 1866, from myo- "muscle" + Latinized form of Greek kardia "heart" (from PIE root *kerd- "heart"). Related: Myocardial; myocardiac; myocarditis.
Entries linking to myocardium
myo-
before vowels my-, word-forming element meaning "muscle," from combining form of Greek mys "muscle," literally "mouse" (see muscle (n.)).
*kerd-
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."