noun
inner part; interior; depths; back
Refers to the physically deep or far part of a space: the back of a drawer, the depths of a forest, the end of a road, etc. Also used for the throat or other body parts.
森の奥に小さな神社がある。
There is a small shrine deep in the forest.
引き出しの奥から古い写真が出
An old photo came out from the back of the drawer.
noun
inner room; living quarters at the back
Specifically the private living area of a traditional Japanese house, located away from the entrance. Often used in the phrase 奥の間.
お客さんを奥の間に通した。
I showed the guest into the inner room.
noun
recesses of the mind; bottom of one's heart; hidden depths
Abstract use: the deep, hidden, or true part of one's mind, heart, or an art. Common in expressions like 心の奥 and 言葉の奥.
彼の言葉の奥には深い悲しみが感じられた。
I could sense deep sadness behind his words.
心の奥では、彼女も同じことを考えていた。
Deep down, she was thinking the same thing.
内 refers to the inside or interior in a general sense, often with a sense of 'within' or 'among'. 奥 emphasizes the deep, far, or hidden part of a space or mind.
裏 means the back side or reverse of something, often with a nuance of 'behind' or 'hidden from view'. 奥 is more about depth and interiority rather than the opposite side.
The kanji 奥 combines 宀 (roof) and 釆 (ancient component suggesting depth or interior). The word おく is native Japanese, and its exact derivation is uncertain.