"aiding the memory," 1753, back-formation from mnemonics, or from Greek mnemonikos "of or pertaining to memory," from mnemon (genitive mnemonos) "remembering, mindful," from memne "memory, a remembrance, record, an epitaph; memory as a mental faculty," from base of mnasthai "remember," from PIE root *men- "to think" (see mind, n.). The noun meaning "mnemonic device" is from 1858. Related: Mnemonical (1660s).