Add

google

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late Middle English: from Latin addere, from ad- ‘to’ + the base of dare ‘put’.

wiktionary

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From Latin addō(“add, give unto”), from ad(“to”) + dō(“give”).

etymonline

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add (v.)

late 14c., "to join or unite (something to something else)," from Latin addere "add to, join, attach, place upon," literal and figurative, from ad "to" (see ad-) + -dere, combining form meaning "to put, place," from dare "to give" (from PIE root *do- "to give").

Intransitive meaning "to do sums, do addition" also is from late 14c. Related: Added; adding. To add up is from 1754; in the figurative meaning "make sense," 1942. Adding machine "machine to cast up large sums" is from 1822.