heart

Unlike most word-building elements in English, heart is not a Latin or Greek import — it is one of the oldest native English words, from Old English heorte, going back to Proto-Germanic hertō. But it is far from alone. Trace it back further and heart meets the Latin cor / cord- (as in cardiac's Latin cousin cordial, record, courage) and the Greek kardia (cardiac) at a shared Proto-Indo-European root ḱerd-, 'heart.' The same beating organ, named three times by three branches of one ancient family.

In English the word stayed close to home and grew rich with meaning. Start with the literal organ: a doctor listens to your heart, and each pulse is a heartbeat. From the organ came the idea of the inner self — the heart was imagined as the seat of feeling and will, so we learn by heart, pour out our hearts, and have a change of heart. From 'the vital center of a person' came 'the vital center of anything': the heart of the city, the heart of the matter. And from 'the seat of will and feeling' came courage — to lose heart is to lose the will to go on, to take heart is to recover it.

The family grows by attaching everyday endings. Add the adjective ending to get hearty — literally 'full of heart,' which splits into two natural senses: a hearty welcome is warm and sincere (coming straight from the heart), while a hearty meal is generous and filling (the kind that gives you strength). Add the verb-forming -en (as in strengthen, darken) to get hearten — to 'put heart into' someone, to encourage; prefix it with dis- ('remove') and you get dishearten — to take the heart out of someone, to discourage. Compounds paint pictures: heartrending news literally 'rends' (tears) the heart, and a light-hearted mood is one where the heart feels light, carrying no burden.

The whole family runs on one image: the heart as the place where feeling, courage, and life itself are stored. Put heart in → hearten; take it out → dishearten; tear it → heartrending; lighten it → light-hearted.