A mnemonic device is a tool used to help remember information. It can be a phrase, rhyme, acronym, image, or any other type of memory aid. The two crossword solutions for the term mnemonic device are 'CUE' (3 letters) and 'REMINDER' (8 letters). A CUE is a signal that helps to recall something, while a REMINDER is a prompt that helps to jog one's memory. Both of these terms are used to describe mnemonic devices, which are tools used to help people remember information.