The term DECLARE UNFIT can be defined as DISQUALIFY, which is a 10 letter word. This term is used to describe the process of officially declaring someone or something as not suitable for a particular purpose. It is often used in the context of legal proceedings, where a court or other authority may declare a person or thing unfit for a certain purpose. For example, a court may declare a person unfit to stand trial due to mental illness. In other contexts, such as sports, it may refer to the disqualification of a competitor from a competition due to a violation of the rules.