*do-

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").

The 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," by 1942. Adding machine "machine to cast up large sums" is from 1822.

1670s, "secret or private stories," from French anecdote (17c.) or directly from Medieval Latin anecdota, from Greek anekdota "things unpublished," neuter plural of anekdotos, from an- "not" (see an- (1)) + ekdotos "published," from ek- "out" (see ex-) + didonai "to give" (from PIE root *do- "to give").

Procopius' 6c. Anecdota, unpublished memoirs of Emperor Justinian full of court gossip, gave the word a sense of "revelation of secrets," which decayed in English to "brief, amusing story" (1761).