How to say "outer" in Japanese

• 外側そとがわCommon
  no-adjectiveThe common word for the literal sense of 'outer': the outside or exterior of a physical thing, its outer side as opposed to the inside, as of a box, a wall or a building.
  水みずは外側そとがわから供給きょうきゅうされた。↗

  Water was supplied from outside.
• 上うわJLPT N3approx.
  noun, prefixIts senses are upper, upward, outer and surface, but for 'outer' it is marginal: it really conveys 'upper' or 'surface', and is seldom the word you want when you mean the outside of something.
• アウター
  prenominal modifierA loanword used chiefly in clothing and fashion talk for outerwear — garments worn on the outside, such as coats and jackets — not for the outside of objects or abstract 'external' senses.
• 外なるそとなる
  pre-noun adjectivalAn uncommon word for abstract uses: 'outer' as in the outer self, and 'external' as in conflict, tension or competition coming from outside rather than within — not the physical outside of objects.

Use 外側 for the outside or exterior of physical things, 「アウター」 for outerwear when talking about clothes, 「外なる」 for abstract senses like the outer self or external conflict, and 上（うわ） rarely, as it really means upper or surface.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 外側そとがわexterior
• 上うわupper
• アウターouter
• 外なるそとなるouter (self, etc.)
• ＯＵＴアウトouter