急きゅう発はっ展てんMeaningsNoun1. boom (development, sales, etc.)Kanji used急hurry発let out展exhibitComposed of急きゅうsudden; abrupt; unexpected; urgent; pressing; steep; sharp; precipitous; rapid; swift; …Na-adjective発はっ展てんdevelopment; growth; expansion; extension; flourishing; development (of a situation, story, etc.); advancement; progression; unfolding; playing around (sexually; esp. of a male homosexual); …Noun