一心不乱 いっしんふらん Meanings な-adjective, Noun wholeheartedly; with heart and soul; intently; with undivided attention; with intense concentration; single-mindedly Kanji 一 one. Read as イチ. 心 heart. Read as シン. 不 un- 乱 disorder. Read as ラン. Word lists Yojijukugo (四字熟語) Jinuma: Japanese Dictionary · Word lists