Being able to place the word absent instead of canceling

Clients have to indicate in Aniday if their dog does not come but because of the word cancel they still think that the payment is removed but that is not the case because we work with subscriptions. It would be nice if I could change this word and that people could indicate this even on the day itself so that I don't get calls every morning about why the dog isn't coming and thus start an (unnecessary) conversation.