1. at a speed less than the speed of sound
Usage: technical; aviation

Examples

• The aircraft flew subsonically to avoid creating a sonic boom over populated areas.
• Commercial airliners typically cruise subsonically at about 500-600 mph.
• The prototype was designed to operate both subsonically and supersonically.
• Military jets often approach targets subsonically to reduce noise detection.
• The wind tunnel tested models moving subsonically through the air.
• Helicopters operate subsonically due to their rotor design limitations.