whyvswhy'sWhat's the difference?

Quick tell: why is a adverb, why's is a contraction, so they fill different roles in a sentence.

Which to use

“why” is an adverb and “why's” is a contraction - they look or sound alike but fill different roles in a sentence.

#125
“why” frequency rank
#28,792
“why's” frequency rank
28917
confusion score

Side-by-Side Comparison

Feature why why's
Definition For what cause, reason, or purpose. Contraction of why + is.

Where the spellings diverge

Shared letters are muted; the letters that actually set why and why's apart are highlighted. They share 3 letters in sequence, which is exactly why the eye skips the difference.

3 ch
why
5 ch
why's

Spelling & Dictionary Insight

Our dataset has no pronunciation recorded for both members, so the reliable separator here is grammatical: why is anadverb and why'sacontraction. On the page they differ by 2 extra letter(s) - “why” sits inside “why's”. Our composite confusion score for this pair is 28917, derived from the frequency rank of both members and their visual similarity.

why is recorded at frequency rank #125, classified as anadv, pronounced /wæ/. why's is at rank #28,792, 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 28917, this pair ranks #367,236 of 530,003 scored English confusable pairs - roughly mid-pack for confusability.

Orthographic DNA of why vs why's

Shared letters: hwy. Private to "why": -. Private to "why's": s.

"why" · 3 letters · shape CCV  ·  "why's" · 4 letters · shape CCVC

Frequency comparison

why#125
why's#28,792

Source: FrequencyWords open word-frequency list

Frequently Asked Questions

Can "why" and "why's" be used interchangeably?
No - they are not even the same part of speech. "why" is an adverb and "why's" a contraction, so a sentence built for one is usually ungrammatical with the other.
Which is more common, "why" or "why's"?
"why" is the more common of the two: it sits at frequency rank #125 in our English list, against #28,792 for "why's". That is a wide gap, so in ordinary text the rarer spelling is the one worth double-checking.

Remembering why vs why's

The fastest way to pick the right one every time.

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

Source: Wiktionary (via kaikki.org) Structured Wiktionary extract

Source: FrequencyWords open word-frequency list FrequencyWords open word-frequency list