sei vs son, What's the Difference?

Which to use

“sei” and “son” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.

#34,681
“sei” frequency rank: #534
“son” frequency rank: 35215
confusion score

Side-by-Side Comparison

Feature	sei	son
Definition	A sei whale.	One's male offspring.

Where the eye mixes sei and son

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

3 ch

sei

3 ch

son

Visual trap between sei and son

A purely visual mix-up. sei (/seɪ/) and son (/sʌn/) are said differently, so reading them aloud is the quickest way to catch the wrong one. On the page they stay close: they share most of their letters but differ in 2 positions. Our composite confusion score for this pair is 35215, derived from the frequency rank of both members and their visual similarity.

sei is recorded at frequency rank #34,681, classified as anoun, pronounced /seɪ/. son is at rank #534, tagged as anoun, pronounced /sʌn/.

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 35215, this pair ranks #313,909 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of sei vs son

Shared letters: s. Private to "sei": ei. Private to "son": no.

"sei" · 3 letters · shape CVV · "son" · 3 letters · shape CVC

Frequently Asked Questions

Do "sei" and "son" mean the same thing in a sentence?

No. They are said differently (/seɪ/ versus /sʌn/) and carry different meanings; reading the sentence aloud is usually enough to catch the wrong one.

In ordinary English text, does "sei" or "son" show up more?

"son" is the more common of the two: it sits at frequency rank #534 in our English list, against #34,681 for "sei". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

After this comparison

Eye-level mix-up between "sei" and "son" is sorted above. Next: full entries or other pairs that share a letter shape.

Full dictionary entry for "sei" with definition, IPA, and generated misspellings. Word entry
Full dictionary entry for "son" - compare definitions side by side with the headword page. Word entry
This pair ranks #313,909 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
"sei" and "son" also get mixed up with nearby pairs, the highest-scored neighbour is "sei vs Sif". Nearby pair

Confusion rank #313,909 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.