1. a floating device that detects underwater sounds and transmits the information by radio
Usage: military; naval

Examples

• The navy deployed sonobuoys to track the submarine’s movement.
• Aircraft dropped sonobuoys in a grid pattern across the search area.
• The sonobuoy detected engine noise from the vessel below.
• Modern sonobuoys can transmit data for several hours before their batteries die.
• The pilot released a sonobuoy to monitor underwater activity.
• Each sonobuoy contains sensitive hydrophones to pick up acoustic signals.