Sailer meaning : That which sails; a boat. A fastball that skims through the air. A person in the business of navigating ships or other vessels Someone knowledgeable in the practical management of ships. A member of the crew of a vessel; a mariner; a common seaman. A person who sails sailing boats as a sport or recreation. Any of various nymphalid butterflies of the genera Neptis, Pseudoneptis and Phaedyma, having white markings on a dark base and commonly flying by gliding.