The definition for an antique watch would probably include watches from the 1960's and earlier. This apart antique watches have a "look" and "feel". They are a piece of history, and they have served someone else for years. They represent the company and its history that made them. They signify years of faithful service to someone who wore it every day. This is what attracts collectors to the world of antique watches.
Antique timepieces often possess special beauty of the era and unmatched craftsmanship. Each piece is unique and some possess quite a historical value with their rarity. Although, many antique watches claim to be waterproof or resistant, it is advisable not to consider them so.
Mechanical watches can last a century and more with proper care and maintenance. Manual wind watches should be wound once a day approximately around the same time. Automatic wind pieces should be wound by wearing the watch or utilizing winders to have watches properly "exercised", thereby extending the time period between expensive overhauls.
All mechanical watches, vintage or otherwise should be overhauled by qualified watchmakers in every of 3 to 5 years in order to maintain the movements in proper conditions. With proper maintenance and care your special piece will be fit as a fiddle.
Antique watches have survived for many decades by being treated well. They are not for everyday wear. They can be easily damaged and so need good care so that they can be a quality heirloom to pass on.