memento Look up memento at Dictionary.com
1401, "Psalm cxxxi in the Canon of the Mass" (which begins with the L. word Memento and in which the dead are commemorated), from L. memento "remember," imperative of meminisse "to remember," a reduplicated form, related to mens "mind." Meaning "reminder, warning" is from 1582; sense of "keepsake" is first recorded 1768. Memento mori "reminder of death" (1592) is from L., lit. "remember that you must die."