The crossword solution for the term OPPOSITE OF CON is PRO, which is a three-letter word. PRO is an abbreviation of the word 'PROFESSIONAL' and is often used to describe someone who is skilled or experienced in a particular activity. It is also used to refer to someone who is in favor of a particular cause or idea. In this context, PRO is the opposite of CON, which is an abbreviation of the word 'CONTRARY' and is often used to describe someone who is against a particular cause or idea.