1. clear, direct, and definite
a categorical denial
This expression emphasizes the meaning and unambiguity behind something, therefore it is usually used in relation to something you feel very strongly about. For example, if you feel you have been falsely accused of something you would make a categorical denial, or categorically deny your guilt. If you say something you truly mean, you state it categorically. While it is used socially, its formal nature means that it is more common in a professional context.