μνημονικός

Greek mnemonikos (μνημονικός) meant 'of or relating to memory,' from mnēmōn, 'mindful,' ultimately from the root *men-, 'to think.' In Greek mythology, Mnemosyne was the Titan goddess of memory. Zeus spent nine nights with her, and she bore the nine Muses. Memory was the mother of all art.

The Greeks took memory training seriously. Simonides of Ceos, around 500 BCE, is credited with inventing the 'method of loci' — the memory palace technique — after a banquet hall collapsed and he found he could identify the dead by remembering where each guest had been sitting. The art of memory was born from disaster, and mnemonics was its name.

Latin kept the Greek word as mnemonicus, and medieval scholars preserved the memory arts through the Dark Ages. Thomas Aquinas studied the method of loci. Giordano Bruno wrote entire books on mnemonic systems. The art of memory was not a party trick — it was a technology for organizing all human knowledge before the printing press made external storage cheap.

English adopted mnemonic in the 1750s. Modern mnemonics range from the humble ('Every Good Boy Does Fine' for musical notes) to the complex (the PAO system used by competitive memorizers). The word has shrunk from a divine art to a study hack, but the technique is the same one Simonides used at that ruined banquet: attach information to places, and you will not forget.