SIDS vs so's, What's the Difference?

Which to use

“SIDS” is a noun and “so's” is a contraction - they look or sound alike but fill different roles in a sentence.

#49,048
“SIDS” frequency rank: #38,171
“so's” frequency rank: 87219
confusion score

Side-by-Side Comparison

Feature	SIDS	so's
Definition	Acronym of sudden infant death syndrome.	So that, in order that.

Where the spellings diverge

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

4 ch

SIDS

4 ch

so's

Spelling & Dictionary Insight

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: SIDS is anoun and so'sacontraction. On the page they share most of their letters but differ in 2 positions. Our composite confusion score for this pair is 87219, derived from the frequency rank of both members and their visual similarity.

SIDS is recorded at frequency rank #49,048, classified as anoun. so's is at rank #38,171, tagged as acontraction.

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 87219, this pair ranks #7,916 of 530,003 scored English confusable pairs - among the most confusable pairs.

Orthographic DNA of SIDS vs so's

Shared letters: s. Private to "SIDS": di. Private to "so's": o.

"SIDS" · 4 letters · shape CVCC · "so's" · 3 letters · shape CVC

Known mistypes of this pair

SIDS ← isds · sdis · sidds · sidss · sisd · ssids

Frequency comparison

SIDS#49,048

so's#38,171

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "SIDS" and "so's" be used interchangeably?

No - they are not even the same part of speech. "SIDS" is a noun and "so's" a contraction, so a sentence built for one is usually ungrammatical with the other.

Which is more common, "SIDS" or "so's"?

"so's" is the more common of the two: it sits at frequency rank #38,171 in our English list, against #49,048 for "SIDS". The two are close in frequency, so neither is a safe default; check the meaning rather than guessing.

Remembering SIDS vs so's

The fastest way to pick the right one every time.

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