To tip over or turn upside down, especially for a boat or ship.
From Spanish 'cabezada' or possibly Dutch/Spanish nautical terminology. The exact origin is debated among etymologists, but it appeared in English maritime vocabulary by the 1700s and became a technical sailing term.
Nobody's quite sure where 'capsize' comes from—it's one of English's mysterious words that appeared in shipyards and spread across the ocean without a clear origin story. That uncertainty is fitting for a word describing a sudden, chaotic loss of control on water.
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