Inner means on the inside, or private to a person. The inner wall, an inner room, inner thoughts.
It is used only before a noun — you cannot say the room is inner. Common phrases: inner city, meaning the older central districts of a city and often the poverty in them; inner circle, the small group closest to somebody powerful; inner ear; inner tube. The psychological uses are everywhere: inner peace, inner voice, inner child. The opposite is outer, which behaves the same way.
1adjectiveinnerOn the inside.
“The inner wall is the one that is damp.”
2adjectiveprivatePrivate to a person; not shown.
“His inner life was a complete mystery to everybody.”
Too few real examples of this word to estimate which sense is commonest.
inner is a position inside.
Old English innera is a comparative of in — it originally meant more inward. English kept a small family of these directional comparatives: inner, outer, upper, under and nether, none of which behave like ordinary adjectives.
Proto-Indo-European
*h₁en
Old English
innera
Middle English
inner
English, today
inner
Built from
From Middle English inner, ynner, ynnere, from Old English innera, comparative of inne (“within”), from Proto-Indo-European h₁en.
Etymology from Wiktionary, CC BY-SA