belső

Etymology
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Adjective

 * 1) interior, internal, inner, inside, end-/endo- having to do with the inner part of something

Noun

 * 1)  interior, inside
 * 2) inner tube an inflatable rubber tube inserted into the casing of a pneumatic tyre / tire
 * 1) inner tube an inflatable rubber tube inserted into the casing of a pneumatic tyre / tire

Declension
In the sense “interior” or “inside”, the possessive is used; in the sense “inner tube”,.