datebook
noun /ˈdeɪtbʊk/
  /ˈdeɪtbʊk/
(all North American English) (British English diary)
- a book or an app with spaces for each day of the year in which you can record things you have to do in the future- I wrote it down in my datebook so I wouldn’t forget.
 Oxford Collocations Dictionaryverb + datebook- note something down in
- put something (down) in
- write something (down) in
- …
 - in a/your datebook