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 
Example Sentences
Recent Examples on the Web Zircon also has a shorter range than conventional, subsonic cruise missiles, meaning Russian subs would have to creep closer to their target to launch their weapons. 
Kyle Mizokami, Popular Mechanics, 9 Aug. 2022 The missile is designed to fly low over the waves at subsonic speeds to avoid radar detection, has a 500-pound warhead, and a range in excess of 67 nautical miles. Kyle Mizokami, Popular Mechanics, 25 May 2022 But whereas the earlier team found Kolmogorov scaling—the subsonic turbulent flow underlying the convection currents in stars as well as Earth's atmosphere—the Australian duo found supersonic turbulence. Jennifer Ouellette, Ars Technica, 30 Nov. 2021 If the pilot ejected at a high subsonic speed, say about 600 knots, the chute would remain reefed; that is, restricted by a cord from opening to its full diameter. Kevin V. Brown, Popular Mechanics, 17 June 2021 And so, the lower ends are usually taken by mammals, from the subsonic utterances of giraffes, elephants and hippos to the sounds of monkeys and cats. Peter Hemminger, Longreads, 3 Mar. 2022 Kalibr, similar to the American Tomahawk missile, is a subsonic cruise missile with a 1,000-pound, high-explosive warhead and a range of up to 1,500 miles. Kyle Mizokami, Popular Mechanics, 11 Feb. 2022 The subsonic Kalibr, with its thousand-pound warhead and range of a thousand miles or more, is indicative of this modernization. David Axe, Forbes, 19 Jan. 2022 Boom is designing Overture to carry between 65 and 88 passengers at subsonic speeds over land and supersonic speeds over water—more than twice as fast as current commercial aircraft. Eric Berger, Ars Technica, 26 Jan. 2022 See More
Kyle Mizokami, Popular Mechanics, 9 Aug. 2022 The missile is designed to fly low over the waves at subsonic speeds to avoid radar detection, has a 500-pound warhead, and a range in excess of 67 nautical miles. Kyle Mizokami, Popular Mechanics, 25 May 2022 But whereas the earlier team found Kolmogorov scaling—the subsonic turbulent flow underlying the convection currents in stars as well as Earth's atmosphere—the Australian duo found supersonic turbulence. Jennifer Ouellette, Ars Technica, 30 Nov. 2021 If the pilot ejected at a high subsonic speed, say about 600 knots, the chute would remain reefed; that is, restricted by a cord from opening to its full diameter. Kevin V. Brown, Popular Mechanics, 17 June 2021 And so, the lower ends are usually taken by mammals, from the subsonic utterances of giraffes, elephants and hippos to the sounds of monkeys and cats. Peter Hemminger, Longreads, 3 Mar. 2022 Kalibr, similar to the American Tomahawk missile, is a subsonic cruise missile with a 1,000-pound, high-explosive warhead and a range of up to 1,500 miles. Kyle Mizokami, Popular Mechanics, 11 Feb. 2022 The subsonic Kalibr, with its thousand-pound warhead and range of a thousand miles or more, is indicative of this modernization. David Axe, Forbes, 19 Jan. 2022 Boom is designing Overture to carry between 65 and 88 passengers at subsonic speeds over land and supersonic speeds over water—more than twice as fast as current commercial aircraft. Eric Berger, Ars Technica, 26 Jan. 2022 See More Word History
Etymology
International Scientific Vocabulary
First Known Use
1920, in the meaning defined at sense 3