sincevssinusWhat's the difference?

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

Which to use

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

#175
“since” frequency rank
#20,225
“sinus” frequency rank
20400
confusion score

Side-by-Side Comparison

Feature since sinus
Definition From a specified time in the past. 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).

Where the eye mixes since and sinus

Muted = shared; highlighted = the visual trap. They share 3 letters in sequence.

5 ch
since
5 ch
sinus

Why the eye confuses since with sinus

These two trip readers on the page rather than in the ear: since is /sɪn(t)s/ while sinus is /ˈsaɪ.nəs/. Spoken aloud the problem disappears. In writing it persists, because they share most of their letters but differ in 2 positions, and the parts of speech differ too (adverb vs noun), which is usually the fastest check. Our composite confusion score for this pair is 20400, derived from the frequency rank of both members and their visual similarity.

since is recorded at frequency rank #175, classified as anadv, pronounced /sɪn(t)s/. sinus is at rank #20,225, tagged as anoun, pronounced /ˈsaɪ.nəs/.

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 20400, this pair ranks #431,346 of 530,003 scored English confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of since vs sinus

Shared letters: ins. Private to "since": ce. Private to "sinus": u.

"since" · 5 letters · shape CVCCV  ·  "sinus" · 5 letters · shape CVCVC

Known mistypes of this pair

  • sinceisnce · sicne · sincce · sinec · sinnce · snice · ssince
  • sinusisnus · sinnus · sinsu · sinuss · siuns · snius · ssinus

Frequently Asked Questions

Can "since" and "sinus" be used interchangeably?
No - they are not even the same part of speech. "since" is an adverb and "sinus" a noun, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "since" or "sinus"?
"since" is the more common of the two: it sits at frequency rank #175 in our English list, against #20,225 for "sinus". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

What to do next

Visual near-miss handled. Browse the word pages or a neighbour when the next look-alike shows up.

  • Full dictionary entry for "since" with definition, IPA, and generated misspellings. Word entry
  • Full dictionary entry for "sinus" - compare definitions side by side with the headword page. Word entry
  • This pair ranks #431,346 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
  • "since" and "sinus" 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 #431,346 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