任意|にんいnin'i[1]atamadaka (head-high)

1. no-adjective, na-adjectiveoptional; voluntary; arbitrary; random; discretionary; facultative; spontaneous; any
2. no-adjective, na-adjective, matharbitrary

• Synonym随意ずいいWrittenWritten/formal word for following one's own will without restriction, as in 「随意に選ぶ」; close to 「任意」, which also covers picking without any set criteria.
• Related勝手かってNeutralColloquial for acting at will or selfishly, often with a negative tinge, as in 「勝手にする」; 「任意」 is a neutral, formal term for what is voluntary or optional.
• Related自主的じしゅてきNeutralActing on one's own initiative without others' instructions, as in 「自主的に参加する」; 「任意」 stresses that something is optional and not compulsory.
• Related自発的じはつてきNeutralDoing things spontaneously, from one's own initiative; 「任意」 means something may be done or skipped, or picked without restriction, as in 「任意の数」.
• Related裁量さいりょうWrittenFormal word for the discretion to decide matters by one's own judgement, as in 「裁量に任せる」; 「任意」 simply means doing something is optional.
• Related主体的しゅたいてきNeutralActing proactively as the agent of one's own actions; 「任意」 stresses that an action is not compulsory and may be done or not.
• Related気ままきままNeutralSomewhat colloquial for doing as one pleases, free of constraints; 「任意」 is the formal term for voluntary and optional.
• RelatedフリーハンドNeutralLoanword for drawing freehand without ruler or compass, or figuratively a free hand in deciding; 「任意」 means optional.
• Related自由じゆうNeutralA very broad word for freedom from restraint, doing as one wishes; 「任意」 focuses on being optional or freely chosen.
• Related無作為むさくいWrittenFormal term for random, leaving selection to chance with no deliberate choice, as in 「無作為抽出」; 「任意」 in maths also means choosing arbitrarily.
• RelatedランダムNeutralCommon loanword for random, frequent in everyday use; 「任意」 leans toward voluntary or arbitrary selection.
• Related随意的ずいいてきWrittenWritten and rather rare; means freely selectable. In everyday speech 「任意の」 is the usual choice.
• Related自由意志じゆういしWrittenFormal term for free will, the capacity to choose and act without outside coercion; 「任意」 describes what may be chosen voluntarily.
• Related自由裁量じゆうさいりょうWrittenFormal term for the scope or power to decide freely at one's discretion; 「任意」 stresses that something is not compulsory.
• Antonym強制きょうせいNeutralAntonym: forcing someone to comply; the opposite of the voluntary nature of 「任意」, as in 「任意捜査と強制捜査」.
• Antonym義務ぎむNeutralAntonym: a duty one must perform; the opposite of 「任意」, where doing or not doing is up to you.
• Antonym必須ひっすNeutralAntonym: indispensable or required, as in 「必須項目」; the opposite of 「任意」, which marks items as optional.

Use 「任意」 for what is voluntary and optional or chosen without restriction, as in 「任意保険」 and 「任意の数」. For acting on one's own initiative pick 「自主的」; for random selection 「ランダム」 or 「無作為」; for doing as one pleases 「勝手」; for what must be included, 「必須」.

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

1. その者ものの意志いしに任まかせること。自由じゆうに行おこなうこと。してもよく、しなくてもよいこと。どのようにしてもよいこと。
2. 特定とくていの選び方えらびかたによらずに選えらぶこと。自由じゆうに選えらぶこと。また自由じゆうに選えらんだおのおのすべて。
3. 相手方あいてがたの同意どういを得えて行おこなうこと。