sinusvsSiriusWhich spelling fits?

Quick tell: sinus is a noun, Sirius is a name, so they fill different roles in a sentence.

Which to use

“sinus” is a noun and “Sirius” is a name - they look or sound alike but fill different roles in a sentence.

#20,225
“sinus” frequency rank
#20,774
“Sirius” frequency rank
40999
confusion score

Side-by-Side Comparison

Feature sinus Sirius
Definition 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). A telescopic binary star, visually the brightest star in the night sky, a part of the northern constellation of Canis Major (the Greater Dog), one of three stars in the Winter Triangle asterism. Long understood as a single extremely luminous white star, it was associated in ancient Egypt with the Nile flood and in Greek and Roman culture with the "dog days" of summer.

Where the eye mixes sinus and Sirius

Muted = shared; highlighted = the visual trap. They share 4 letters in sequence. sinus runs 5 letters (CVCVC) against Sirius's 6 (CVCVVC) - the length gap alone is often enough to separate them once you know to check it.

5 ch
sinus
6 ch
Sirius

Look-alike desk: sinus vs Sirius

These two trip readers on the page rather than in the ear: sinus is /ˈsaɪ.nəs/ while Sirius is /ˈsɪɹi.əs/. Spoken aloud the problem disappears. In writing it persists, because they differ by 1 letter(s) in length, and the parts of speech differ too (noun vs name), which is usually the fastest check. Our composite confusion score for this pair is 40999, derived from the frequency rank of both members and their visual similarity.

sinus is recorded at frequency rank #20,225, classified as anoun, pronounced /ˈsaɪ.nəs/. Sirius is at rank #20,774, tagged as aname, pronounced /ˈsɪɹi.əs/.

Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.

With a confusion score of 40999, this pair ranks #262,461 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of sinus vs Sirius

Shared letters: isu. Private to "sinus": n. Private to "Sirius": r.

"sinus" · 5 letters · shape CVCVC  ·  "Sirius" · 6 letters · shape CVCVVC

Known mistypes of this pair

  • sinusisnus · sinnus · sinsu · sinuss · siuns · snius · ssinus
  • Siriusisrius · siirus · sirisu · siriuss · sirrius · siruis · sriius · ssirius

Frequently Asked Questions

Do "sinus" and "Sirius" mean the same thing in a sentence?
No - they are not even the same part of speech. "sinus" is a noun and "Sirius" a name, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "sinus" or "Sirius"?
"sinus" is the more common of the two: it sits at frequency rank #20,225 in our English list, against #20,774 for "Sirius". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

After this comparison

Pronunciation already separates them, if the page still looks alike, the dictionary links below settle it.

  • Full dictionary entry for "sinus" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "Sirius" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #262,461 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "sinus" and "Sirius" also get mixed up with nearby pairs, the highest-scored neighbour is "SIDS vs sinus". Nearby pair
  • Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes

Confusion rank #262,461 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list