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

Ship started reentering our planet's atmosphere about two hours and 40 minutes after launch and went subsonic — breaking the sound barrier, in the fast-to-slow direction — 26 minutes later. — Mike Wall, Space.com, 28 Sep. 2026

According to Tianmushan Laboratory, future versions will require a variable-cycle propulsion system capable of supporting both supersonic and subsonic flight efficiently. — Bojan Stojkovski, Interesting Engineering, 20 Sep. 2026

There are widespread reports of intrusive noise, both in the audible and subsonic ranges, that is not restricted to the centers’ footprint. — Letters To The Editor, The Orlando Sentinel, 5 Aug. 2026

In particular, the shape of the weapon looks much like a conventional subsonic cruise missile. — Geoff Brumfiel, NPR, 18 June 2026

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