KANJI GUIDE
A wave. 波乱 is upheaval; 電波 is a radio wave.
A leaf. 言葉, the word for language, is literally leaves of speech.
The sky, and heaven with it. 天国 is paradise; 天気 is the weather.
The character in 武士道, the way of the samurai, and in 柔道. Read dō, and the head of it is taken for do.