subsonic

adjective

sub·​son·​ic ˌsəb-ˈsä-nik 

1

: of, relating to, or being a speed less than that of sound in air

2

: moving, capable of moving, or utilizing air currents moving at a subsonic speed

3

: infrasonic sense 1

subsonically

ˌsəb-ˈsä-ni-k(ə-)lē 

adverb

Examples of subsonic in a Sentence

Recent Examples on the Web

By contrast, Musk’s capsule would travel at subsonic speeds in a much softer vacuum, a concession that allows his pod to be borne on a cushion of air (and still be propelled electromagnetically). —IEEE Spectrum, 18 Dec. 2015

Finally, there is a subsonic filter for eliminating any unwanted ultra‑low frequencies. —Mark Sparrow, Forbes.com, 20 Apr. 2025

The air, compressed to subsonic speeds, mixes with fuel (typically hydrogen) and ignites in a combustion chamber. —Michael Verdon, Robb Report, 22 Mar. 2025

Boom’s plan is that Overture will be in operation before the end of the decade, carrying 64 to 80 passengers at Mach 1.7, about twice the speed of today’s subsonic airliners. —Maureen O'Hare, CNN, 3 Mar. 2025

Word History

Etymology

International Scientific Vocabulary

First Known Use

1920, in the meaning defined at sense 3

Rhymes for subsonic

• atonic
• benthonic
• bionic
• bosonic
• bubonic
• canonic
• carbonic
• cyclonic
• demonic
• dystonic
• hadronic
• harmonic

Kids Definition

subsonic

adjective

sub·​son·​ic ˌsəb-ˈsän-ik 

ˈsəb-

1

: of, relating to, or being a speed less than that of sound in air

2

: moving, capable of moving, or using air currents moving at a subsonic speed