seat·er \ˈsēd.ə(r), -ētə-\noun (-s) 1. a.: one that puts in seats < a chair seater > b.: a tool or implement for adjusting or fitting something (as a valve) into its seat 2.archaic: one (as an usher) who apportions seats or assigns persons to seats 3.: something (as a vehicle) provided with seats especially of a specified number — usually used in combination < toured the countryside in a four-seater >