SUBSONIC
Meaning of SUBSONIC in English
/ ˌsʌbˈsɒnɪk; NAmE -ˈsɑːn-/ adjective
less than the speed of sound; flying at less than the speed of sound
—compare supersonic
Oxford Advanced Learner's English Dictionary.
Оксфордский английский словарь для изучающик язык на продвинутом уровне.
2005