Plural of dorsum; the backs or upper surfaces of structures, particularly in anatomy (like the back of the hand or foot).
From Latin 'dorsum' (back), the standard plural form 'dorsa' maintained in scientific and medical terminology across multiple languages.
The word 'dorsal' comes from the same Latin root, so whenever you hear 'dorsal fin' on a fish, you're using the adjective form of the word that anatomists use for 'back.'
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