This is an excerption from an invitation email template:
We meet on Wednesday evenings during term time. We would be honored if you would accept this invitation to join us on a Wednesday evening. Our diary for the coming year is still quite flexible, but the most ideal dates for us would be ...
I looked up the dictionary and there are two meanings for the word "diary".
- (North American English datebook) a book with spaces for each day of the year in which you can write down things you have to do in the future
- a book in which you can write down the experiences you have each day, your private thoughts, etc.
I reckon the bold "diary" fits definition 1 best. But I wonder if it a typical use of diary this word. If it were me, I would choice "schedule" or "plan".
Our schedule for the coming year is still quite flexible... Our plan for the coming year is still quite flexible