一心不乱|いっしんふらんisshinfuran

1. na-adjective, nounwholeheartedly; with heart and soul; intently; with undivided attention; with intense concentration; single-mindedly
   自分じぶんの仕事しごとに一心いっしん不乱ふらんに打ち込うちこみなさい。↗

   Give yourself to your work with body and soul.

• Synonym一心いっしんWrittenWritten word stressing wholehearted devotion or many people being of one mind, often as 「一心に祈る」; works as an adverb and is shorter than the four-character term.
• Synonym無我夢中むがむちゅうNeutralStresses being so absorbed you forget yourself and everything else; also used in urgent situations like 「無我夢中で逃げる」. 「一心不乱」 stresses freedom from distracting thoughts.
• Synonym専念せんねんWrittenWritten word for putting all your energy into one thing alone, as in 「治療に専念する」; usually about devoting yourself to a task. 「一心不乱」 stresses an undistracted mind more.
• Synonym熱中ねっちゅうNeutralStresses being absorbed out of personal interest, as in 「ゲームに熱中する」; carries more of a sense of fondness than 「一心不乱」.
• Synonym専心せんしんWrittenMeans concentrating your mind on one thing, as in 「研究に専心する」; plainer than 「一心不乱」 and less frequently used.
• Synonym没頭ぼっとうWrittenWritten word for forgetting all else and burying yourself in something, as in 「研究に没頭する」; it can be used directly as a verb.
• SynonymひたすらWrittenAdverb meaning to keep doing just one thing single-mindedly, as in 「ひたすら謝る」; stresses the action continuing. 「一心不乱」 stresses an undistracted mind.
• Synonym傾注けいちゅうFormalFormal word for pouring energy or devotion into something, as in 「全力を傾注する」; the object is one's energy. Its original sense is pouring out liquid.
• Synonym集中しゅうちゅうNeutralThe everyday word: attention converging on one point, but also concentration of population or power; very broad. The four-character term stresses undivided focus more.
• Synonym没入ぼつにゅうWrittenWritten word stressing deep immersion, as in 「作品世界に没入する」; it can also mean an object sinking, a sense 「一心不乱」 lacks.
• Related夢中むちゅうNeutralStresses being so captivated you forget other things, as in 「ゲームに夢中」; leans toward fascination. It can also mean being in a dream, unlike 「一心不乱」.
• RelatedコンセントレーションNeutralLoanword for focusing attention, heard mostly in sports and training contexts; in everyday speech 「集中」 is the usual choice.
• Antonym心猿意馬しんえんいばWrittenRare written idiom for a restless mind ruled by desires and emotions; the opposite of 「一心不乱」, which stresses freedom from distraction.

Use 「一心不乱」 to focus on one thing with no distracting thoughts, as in 「一心不乱に勉強する」. For losing yourself in something, choose 「無我夢中」 or 「没頭」; for devoting yourself solely to a task, 「専念」; the everyday word is 「集中」. The opposite is 「心猿意馬」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 1つの事ことに神経しんけい・心こころを集中しゅうちゅうさせ、他たの事ことに気きを取とられたりしないこと。またはその様子ようす。もともとは、「雑念ざつねんを捨すてて心こころを1つにし仏ほとけに帰依きえする」という意味いみの仏語ふつご。