A master tradesman is a person who has a greater level of skill than most in the licensed trades; this is usually granted following instruction, testing and a period of practical experience.
For example, a master plumber, or master electrician is the highest level of plumber or electrician. Many trades contractors are required to have one master on staff, who usually takes the lead role. Compare with journeyman plumber or electrician.
Master was a title originating in England which was used in the Middle Ages for men of fairly high rank, such as gentlemen, priests or scholars.
Master Aircrew is the highest non-commissioned rank held by aircrew in the Royal Air Force.
Masters in athletics, especially track and field, is the name of the category reserved for competition among older athletes; the name of the category for keeping world records for these athletes; and a term for the competitors themselves.