sinus
/ˈsaɪ.nəs/noun
sinus is spelled S-I-N-U-S: 5 letters and 2 syllables. It appears 1.9 times per million words in written English, the 20,101st most frequent word form (wordfreq, 2021 data). As a noun, sinus means “A pouch or cavity in a bone or other tissue, especially one in the bones of the face or skull connecting with the nasal cavities (the paranasal sinus)” (English Wiktionary, September 2026). The plural of sinus is sinuses.
How many letters and syllables are in sinus?
| Letters | 5: S-I-N-U-S |
|---|---|
| Syllables | 2 (from its American pronunciation) |
| In writing | 1.9 times per million words; the 20,101st most frequent word form |
| Wrong spellings searched | none measured in search |
| Same letters |
Sources: letters and syllables from the English Wiktionary's hyphenation or pronunciation and the CMU Pronouncing Dictionary; written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media); rhymes and same-letter words are computed by PlainSpell from its own word list.
How common is sinus?
Sinus appears 1.9 times per million words in written English, the 20,101st 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 sinus?
- /ˈsaɪ.nəs/
Sinus has 2 syllables (counted from its American pronunciation in the CMU Pronouncing Dictionary).
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract). Recordings: LL-Q1860_(eng)-Vealhurl-sinus.wav, Wikimedia Commons (author and licence on each file's page).
What rhymes with sinus?
No other word on PlainSpell ends in the same sounds as sinus.
Spelled with the same letters in another order: nisus.
Computed by PlainSpell from the pronunciations in the English Wiktionary (dump of September 2, 2026): a rhyme shares every sound from the last stressed vowel to the end; ordered by written frequency (wordfreq 3.1).
Forms of sinus
- sinuses plural
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
What does sinus mean?
The meanings the English Wiktionary records, quoted as written there (source below).
noun
- 1
A pouch or cavity in a bone or other tissue, especially one in the bones of the face or skull connecting with the nasal cavities (the paranasal sinus).
- 2
An irregular venous or lymphatic cavity, reservoir, or dilated vessel.
- 3
Relating to or denoting the sinoatrial node of the heart or its function of regulating the heartbeat.
- 4
An abnormal cavity or passage such as a fistula, leading from a deep-seated infection and discharging pus to the surface.
- 5
A rounded notch or depression between two lobes or teeth in the margin of a leaf or petal.
- 6
A bay of the sea; a recess in the shore.
- 7
Synonym of sine.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).
Sinus in Spanish, French, German and Portuguese
In the sense pouch or cavity in a bone or other tissue:
| Language | Words |
|---|---|
| French | sinus |
| German | Sinus, (paranasal) Nasennebenhöhle |
| Portuguese | seio |
| Spanish | cavidad/alvéolo/alveolo sinusal |
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 sinus come from?
Learned borrowing from Latin sinus (“a bent surface, curve, hollow”). Doublet of sine.
Source: English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0), through kaikki.org (Wiktextract).