subsonic
adjective, noun
subsonic is spelled S-U-B-S-O-N-I-C: 8 letters. It appears about once in every 3 million words in written English, the 51,738th most frequent word form (wordfreq, 2021 data). As an adjective, subsonic means “having a frequency too low to be audible” (English Wiktionary, September 2026).
How many letters and syllables are in subsonic?
| Letters | 8: S-U-B-S-O-N-I-C |
|---|---|
| In writing | about once in every 3 million words; the 51,738th most frequent word form |
| Wrong spellings searched | none measured in search |
Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How common is subsonic?
Subsonic appears about once in every 3 million words in written English, the 51,738th most frequent word form in the list.
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How do you pronounce subsonic?
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Vealhurl-subsonic.wav, Wikimedia Commons (author and licence on each file's page).
Forms of subsonic
- subsonics plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
What does subsonic mean?
The meanings the English Wiktionary records, quoted as written there (source below).
adjective
- 1
having a frequency too low to be audible
- 2
very quiet, almost inaudible
The noise of the ship was all around her. The faint subsonic rumble of the reactor and drive. (Leviathan Wakes, James S. A. Corey)
- 3
(aviation) less than the speed of sound (in the same medium, and at the same temperature and pressure)
- 4
with a Mach number such that 0.3 < Ma < 0.8 (approximately - the exact limits vary between sources)
noun
- 1
an aircraft whose maximum speed is less than the speed of sound
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
Subsonic in Spanish, French, German and Portuguese
In the sense (of a speed) less than the speed of sound:
| Language | Words |
|---|---|
| French | subsonique |
| Portuguese | subsónico, subsônico |
| Spanish | subsónico |
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Translations are Wiktionary's, by sense; a linked word has its own PlainSpell page.
Where does subsonic come from?
From sub- + sonic.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).