Sounder, a book by William H. Armstrong

Echo sounder, a device used to measure water depth using Sonar

Sounder (radio). a station identifier in a radio broadcast

Atmospheric sounder also known as SODAR

Sounder Commuter Rail, a transit system serving the Puget Sound area

Sounder (film), a film based on the novel

Telegraph sounder, a device for detecting operability in a telegraph

Sounder, a member of the Seattle Sounders professional soccer teams

Sounder, a group of wild boar, or of domestic pigs foraging in woodland (in other circumstances a group of domestic pigs is a herd).

Sounder, a device that transmits a signal and uses the returned signal to measure characteristics of the propagation medium.