The definition of a Professional Watch is a watch that is designed for use in professional situations such as diving, flying, exploring, sailing and military situations. Rolex virtually invented the category with the first water-resistant watch in 1926, the Oyster case. They were also the first company to introduce at wristwatch that could show two time zone simultaneously, the GMT, in 1954.
TAG Heuer, Omega, Breitling and IWC, among others, also use the term “Professional” in marketing some of their sports watches.
According to Rolex, “In the early 1950s, thanks to the perfect mastery of chronometric precision and water resistance, Rolex developed professional watches that served as tools and whose functions went far beyond simply telling the time. These watches were intended for new professional activities, such as deep-sea diving, aviation, mountain climbing and scientific exploration.”