What does 室内 mean?
室内 is a Japanese noun meaning “indoor; inside the room” in English. It is written as 室内 in kanji, しつない in hiragana, and shitsunai in romaji. This word is part of JLPT N2 vocabulary.
Example sentence
たとえ外はどんなに寒くとも、室内は気持ちよく暖められている。
No matter how cold it is outside, the rooms are comfortably heated.