一旦緩急 いったんかんきゅう Meanings Expression (when) danger threatens; should an emergency occur Kanji 一 one. Read as イチ. 旦 once. Read as タン. 緩 loose. Read as カン. 急 sudden. Read as キュウ. Word lists Yojijukugo (四字熟語) Jinuma: Japanese Dictionary · Word lists