gas·ser \ˈgasə(r), ˈgaas-, ˈgais-\noun (-s) 1.: one that gasses: as a.: a well (as an oil well) that yields gas b.slang: a talkative or bragging person c.: a worker who singes cloth, yarn, or thread 2.slang: something outstanding of its kind < the new show is a real gasser >