Outdoor or Outdoors? One Is an Adjective
Outdoor describes things that happen outside. Outdoors, with an s, is the adverb and the noun, and mixing them up is a common slip.
Outdoor is the adjective: outdoor clothing, an outdoor pool. Outdoors with an s is the adverb and the noun — we ate outdoors, the great outdoors. The rule is simple and reliable: if it sits in front of a noun, drop the s.
- Happening or used outside (adjective). *Outdoor furniture.*
- Outside (adverb). *They sleep outdoors.*
- The open air (noun). *A love of the outdoors.*
Word forms
| Form | Word | Example |
|---|---|---|
| Adjective | outdoor | Outdoor shoes. |
| Adverb | outdoors | Waiting outdoors. |
| Noun | outdoors | The great outdoors. |
| Opposite | indoor | An indoor court. |
| Opposite | indoors | Stay indoors. |
How it is used in a sentence
- The school has an outdoor classroom.Adjective before a noun.
- We ate outdoors for the first time this year.Adverb after a verb.
- He spends every weekend in the outdoors.Noun.
Pairs that follow the same rule
- Outdoor / outdoors
- Indoor / indoors
- Upstair (rare) / upstairs
- Toward / towards — a different rule; both are adverbs and prepositions
- Backward / backwards — American prefers the shorter form as an adverb
From *out of doors*, an older phrase meaning outside the house. The adverb kept the s of *doors*, and the adjective lost it.
Outdoor or outdoors?
Outdoor before a noun; outdoors everywhere else. An outdoor concert takes place outdoors.
Why does the adverb have an s?
Because it comes from the phrase *out of doors*, where doors was plural. The adjective dropped the ending when it became a single word.