[1] : The Collaborative International Dictionary of English v.0.48

reminder \remind"er\ -?r, n.
   one who, or that which, reminds; that which serves to awaken
   remembrance.
   1913 webster

[2] : WordNet (r) 2.0

reminder
     n 1: a message that helps you remember something; "he ignored his
          wife's reminders"
     2: an experience that causes you to remember something
     3: someone who gives a warning so that a mistake can be avoided
        syn: admonisher, monitor
see also:
admonisher monitor 

[3] : Moby Thesaurus II by Grady Ward, 1.0

47 moby thesaurus words for "reminder":
   admonition, adversaria, aide-memoire, annotation, cue, docket,
   entry, flapper, footnote, gesture, hint, indication, intimation,
   item, jogger, jotting, keepsake, marginal note, marginalia,
   memento, memo, memoir, memorandum, memorial, minutes, mnemonic,
   notation, note, notice, prompt, prompter, prompting, refresher,
   register, registry, relic, remembrance, remembrancer, scholia,
   scholium, sign, souvenir, suggestion, tickler, token, trophy,
   warming

Reminder >> R Words
Reminder, definition of term: Reminder
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