The term 'become defunct' can be summarized as a process of dying or ceasing to exist. It is often used to describe businesses, organizations, or products that have gone out of existence or are no longer in use. The crossword solution for this term is 'DIE, ' which is a three-letter word that implies the end of something. This term is often used to describe the end of a business, organization, or product, and it can also be used to describe the end of a person's life.