Someone who rides a horse, bike, or other vehicle; or an additional clause or condition added to a document.
From Old English 'ridere,' from 'ridan' (to ride). The sense of 'additional clause' comes from something 'riding on' or attached to a main agreement. Popular as a surname in English-speaking countries.
Legal riders are confusing on purpose—companies hide terrible terms in riders attached to contracts, betting you won't notice. The word itself reveals the trick: it's something 'riding along' on the main agreement.
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