nidan verb (upper class) with 'bu' ending (archaic)
act violently; act roughly; act rashly
Archaic Nidan verb (upper class) with 'bu' ending. Found in classical Japanese; not used in modern speech. The meaning is to behave in a wild, violent, or reckless manner.
The archaic word 千早ぶ means to act violently and is not used in modern Japanese.