sí vs sir, What's the Difference?

Which to use

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

#146
“sí” frequency rank: #6,830
“sir” frequency rank: 6976
confusion score

Side-by-Side Comparison

Feature	sí	sir
Definition	Palabra usada para expresar afirmación.	Señor, caballero.

Where the eye mixes sí and sir

Muted = shared; highlighted = the visual trap. They share 1 letter in sequence.

2 ch

sí

3 ch

sir

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: sí is [ˈsi] while sir is /sɜː(ɹ)/. 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 (adverb vs noun), which is usually the fastest check. Our composite confusion score for this pair is 6976, derived from the frequency rank of both members and their visual similarity.

sí is recorded at frequency rank #146, classified as anadv, pronounced [ˈsi]. sir is at rank #6,830, tagged as anoun, pronounced /sɜː(ɹ)/.

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 6976, this pair ranks #309,283 of 323,831 scored Spanish confusable pairs - a relatively easy-to-tell-apart pair.

Orthographic DNA of sí vs sir

Shared letters: s. Private to "sí": í. Private to "sir": ir.

"sí" · 2 letters · shape CV · "sir" · 3 letters · shape CVC

Frequently Asked Questions

Can "sí" and "sir" be used interchangeably?

No - they are not even the same part of speech. "sí" is an adverb and "sir" a noun, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "sí" or "sir"?

"sí" is the more common of the two: it sits at frequency rank #146 in our Spanish list, against #6,830 for "sir". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.