heart (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.

heart (v.)

Old English hiertan "give heart to," from heart (n.). Shakespeare used it as "take to heart" (c. 1600); 1866 of cabbages, "to form a heart." Meaning "to love" is by 1993, from the popular New York state tourism campaign that used the heart symbol in place of the word "love."

Definitions of heart

heart (n.)
the locus of feelings and intuitions;
in your heart you know it is true
Synonyms: bosom
heart (n.)
the hollow muscular organ located behind the sternum and between the lungs; its rhythmic contractions move the blood through the body;
he stood still, his heart thumping wildly
Synonyms: pump / ticker
heart (n.)
the courage to carry on;
you haven't got the heart for baseball
Synonyms: mettle / nerve / spunk
heart (n.)
an area that is approximately central within some larger region;
they ran forward into the heart of the struggle
Synonyms: center / centre / middle / eye
heart (n.)
the choicest or most essential or most vital part of some idea or experience;
the heart and soul of the Republican Party
Synonyms: kernel / substance / core / center / centre / essence / gist / heart and soul / inwardness / marrow / meat / nub / pith / sum / nitty-gritty
heart (n.)
an inclination or tendency of a certain kind;
he had a change of heart
Synonyms: spirit
heart (n.)
a plane figure with rounded sides curving inward at the top and intersecting at the bottom; conventionally used on playing cards and valentines;
he drew a heart and called it a valentine
heart (n.)
a firm rather dry variety meat (usually beef or veal);
a five-pound beef heart will serve six
heart (n.)
a positive feeling of liking;
the child won everyone's heart
Synonyms: affection / affectionateness / fondness / tenderness / warmness / warmheartedness / philia
heart (n.)
a playing card in the major suit that has one or more red hearts on it;
hearts were trumps
he led the queen of hearts