heartbreak n.

Old English heorte "heart (hollow muscular organ that circulates blood); breast, soul, spirit, will, desire; courage; mind, intellect," from Proto-Germanic *hertan- (source also of Old Saxon herta, Old Frisian herte, Old Norse hjarta, Dutch hart, Old High German herza, German Herz, Gothic hairto), from PIE root *kerd- "heart."

Spelling with -ea- is c. 1500, reflecting what then was a long vowel, and the spelling remained when the pronunciation shifted. Most of the modern figurative senses were present in Old English, including "memory" (from the notion of the heart as the seat of all mental faculties, now only in by heart, which is from late 14c.), "seat of inmost feelings; will; seat of emotions, especially love and affection; seat of courage." Meaning "inner part of anything" is from early 14c. In reference to the conventional heart-shape in illustration, late 15c.; heart-shaped is from 1744.

Heart attack attested from 1875; heart disease is from 1864. The card game hearts is so called from 1886. To have one's heart in the right place "mean well" is from 1774. Heart and soul "one's whole being" is from 1650s. To eat (one's own) heart "waste away with grief, resentment, etc." is from 1580s.

c. 1300, "act of breaking, forcible disruption or separation," from break (v.). The sense in break of day "first appearance of light in the morning" is from 1580s; the meaning "sudden, marked transition from one course, place, or state to another" is by 1725.

The sense of "short interval between spells of work" (originally between lessons at school) is from 1861. The meaning "stroke of luck" is attested by 1911, probably an image from billiards (where the break that scatters the ordered balls and starts the game is attested from 1865). The meaning "stroke of mercy" is from 1914. The jazz musical sense of "improvised passage, solo" is from 1920s. The broadcasting sense is by 1941.