Old English brecan "to break, shatter, burst; injure, violate, destroy, curtail; break into, rush into; burst forth, spring out; subdue, tame" (class IV strong verb; past tense bræc, past participle brocen), from Proto-Germanic *brekan (cf. Old Frisian breka, Dutch breken, Old High German brehhan, German brechen, Gothic brikan), from PIE root *bhreg- "to break" (see fraction). Most modern senses were in Old English. In reference to the heart from early 13c. Meaning "to disclose" is from early 13c.
Break bread "share food" (with) is from late 14c. Break the ice is c.1600, in reference to the "coldness" of encounters of strangers. Break wind first attested 1550s. To break (something) out (1890s) probably is an image from dock work, of freeing cargo before unloading it. Ironic theatrical good luck formula break a leg has parallels in German Hals- und Beinbruch "break your neck and leg," and Italian in bocca al lupo. Evidence of a highly superstitious craft (cf. Macbeth).
c.1300, "act of breaking," from break (v.). Sense of "short interval between spells of work" (originally between lessons at school) is from 1861. Meaning "stroke of luck" is attested by 1911, probably an image from billiards (where the break that starts the game is attested from 1865). Meaning "stroke of mercy" is from 1914. Musical sense, "improvised passage, solo" is attested from 1920s in jazz.
Old English heorte "heart; breast, soul, spirit, will, desire; courage; mind, intellect," from Proto-Germanic *khertan- (cf. Old Saxon herta, Old Frisian herte, Old Norse hjarta, Dutch hart, Old High German herza, German Herz, Gothic hairto), from PIE *kerd- "heart" (cf. Greek kardia, Latin cor, Old Irish cride, Welsh craidd, Hittite kir, Lithuanian širdis, Russian serdce "heart," Breton kreiz "middle," Old Church Slavonic sreda "middle").
Spelling with -ea- is c.1500, reflecting what then was a long vowel, and remained when pronunciation shifted. Most of the figurative senses were present in Old English, including "intellect, memory," now only in by heart. Heart attack attested from 1875; heart disease is from 1864. The card game hearts is so called from 1886.
The chambered, muscular organ in vertebrates that pumps blood received from the veins into the arteries, thereby maintaining the flow of blood through the entire circulatory system.
A similarly functioning structure in invertebrates.
According to the Bible, the heart is the centre not only of spiritual activity, but of all the operations of human life. "Heart" and "soul" are often used interchangeably (Deut. 6:5; 26:16; comp. Matt. 22:37; Mark 12:30, 33), but this is not generally the case. The heart is the "home of the personal life," and hence a man is designated, according to his heart, wise (1 Kings 3:12, etc.), pure (Ps. 24:4; Matt. 5:8, etc.), upright and righteous (Gen. 20:5, 6; Ps. 11:2; 78:72), pious and good (Luke 8:15), etc. In these and such passages the word "soul" could not be substituted for "heart." The heart is also the seat of the conscience (Rom. 2:15). It is naturally wicked (Gen. 8:21), and hence it contaminates the whole life and character (Matt. 12:34; 15:18; comp. Eccl. 8:11; Ps. 73:7). Hence the heart must be changed, regenerated (Ezek. 36:26; 11:19; Ps. 51:10-14), before a man can willingly obey God. The process of salvation begins in the heart by the believing reception of the testimony of God, while the rejection of that testimony hardens the heart (Ps. 95:8; Prov. 28:14; 2 Chr. 36:13). "Hardness of heart evidences itself by light views of sin; partial acknowledgment and confession of it; pride and conceit; ingratitude; unconcern about the word and ordinances of God; inattention to divine providences; stifling convictions of conscience; shunning reproof; presumption, and general ignorance of divine things."