- 1reminder (of somebody/something) reminder (that…) something that makes you think about or remember someone or something, that you have forgotten or would like to forget The sheer size of the cathedral is a constant reminder of the power of religion. The incident served as a timely reminder of just how dangerous mountaineering can be. The article concludes with a chilling reminder that the disease can strike anyone at any time. a friendly reminder
- 2 a letter, an e-mail, a note, etc. informing someone that they have not done something If an invoice is not paid within seven days, we automatically send out a reminder.