sei vs sim, What's the Difference?

Which to use

“sei” is a num and “sim” is a verb - they look or sound alike but fill different roles in a sentence.

#48,072
“sei” frequency rank: #14,009
“sim” frequency rank: 62081
confusion score

Side-by-Side Comparison

Feature	sei	sim
Definition	Seis.	Primera persona del singular del presente activo de subjuntivo de sum.

Where the spellings diverge

Shared letters are muted; the letters that actually set sei and sim apart are highlighted. They share 2 letters in sequence, which is exactly why the eye skips the difference.

3 ch

sei

3 ch

sim

Spelling & Dictionary Insight

These two trip readers on the page rather than in the ear: sei is /s̺ej/ while sim is /ˈsim/. 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 (num vs verb), which is usually the fastest check. Our composite confusion score for this pair is 62081, derived from the frequency rank of both members and their visual similarity.

sei is recorded at frequency rank #48,072, classified as anum, pronounced /s̺ej/. sim is at rank #14,009, tagged as averb, pronounced /ˈsim/.

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 62081, this pair ranks #53,205 of 323,831 scored Spanish confusable pairs - among the most confusable pairs.

Orthographic DNA of sei vs sim

Shared letters: is. Private to "sei": e. Private to "sim": m.

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

Frequency comparison

sei#48,072

sim#14,009

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "sei" and "sim" be used interchangeably?

No - they are not even the same part of speech. "sei" is a num and "sim" a verb, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "sei" or "sim"?

"sim" is the more common of the two: it sits at frequency rank #14,009 in our Spanish list, against #48,072 for "sei". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Remembering sei vs sim

The fastest way to pick the right one every time.

Check the role first: if you need a num, it's “sei”; for a verb, it's “sim”.
See each word in full, definition, IPA, etymology and its other confusables. Full “sei” entry
Browse more pairs most likely to be confused. Most confusable