A "professional referee" refers to a person who is officially trained and paid for overseeing and making fair decisions in sports or other competitive events. Full definition
When you know that several people are applying for the same professional referee job, you need every advantage you can to stand out among the crowd. (cover-letter-now.com)
Indeed, City have written to the body in charge of professional referees to raise their concerns and call for retrospective action when referees don't dish out red cards when warranted. (newindianexpress.com)
«There are only two countries where there are professional referees in Europe and that's England and Italy, so of course you want them to use the time to improve and raise their level.» (standard.co.uk)