Well for instance the word "excuse," there is sometimes, at least in my experience some confusion to the use of the word. What I think of it as an "excuse" is an attempt to get off the hook which doesn't work. For instance, lets say a student comes to school one day without their homework done. If their student says their dog ate it that's an excuse. It will not get the student off the hook. The famous, "my dog at it" excuse doesn't work, therefore its an excuse. On the other hand lets say the student was in a car crash on the way home from school the previous day and they broke their arm and they come to class with their arm in a cast and a note from the hospital. In that case they have a reason for not having their homework done and it should get them off the hook. The second case is not an excuse and its not supposed to be as its a reason and the student shouldn't be held responsible for not having their homework done since they really were in a car crash and they really did break their arm and they have their arm in a cast and a note from the hospital to prove it.