随意|ずいいzuii[1]atamadaka (head-high)

1. na-adjective, nounvoluntary; optional; free; elective
   随意ずいいに退席たいせきしてかまいません。↗

   You may leave your seat at will.

• Synonym任意にんいNeutralClosest to the headword: optional, voluntary, as in 「任意保険」「任意に選ぶ」. 「随意」 is more written/formal and stresses doing as one pleases.
• Synonym自由じゆうNeutralThe most widely used word: freedom, no constraints, as in 「自由に選ぶ」「自由な時間」. 「随意」 is the more written/formal choice.
• Related自発的じはつてきNeutralSpontaneous, proactive: stresses acting out of one's own volition, rather than simply having no restrictions as with 「随意」.
• Related自主的じしゅてきNeutralIndependent, autonomous: acting on one's own, free of others' interference; fits people and organizations. 「随意」 stresses being free to choose as one pleases.
• Related裁量さいりょうNeutralDiscretion: handling matters by one's own judgement; stresses that the decision rests with you. Common in administrative contexts.
• Related自由裁量じゆうさいりょうNeutralDiscretionary power: the authority or scope to decide freely on one's own judgement. Legal and administrative term, focused on the extent of that power.
• Related随意的ずいいてきNeutralAdjectival form of the headword: freely selectable at one's own will, stressing optionality. Will-controlled muscles are generally called 「随意筋」.
• Antonym強制きょうせいNeutralAntonym: compulsion or coercion, forcing someone to act. The opposite of 「随意」, where you act as you yourself wish.
• Antonym義務ぎむNeutralAntonym: duty or obligation, something you must do. Contrasts with 「随意」, where doing it or not is up to you.

Use 「随意」 for acting without restrictions, just as you please; it leans written or formal, as in 「ご随意に」「随意契約」. For something optional say 「任意」, for freedom in general 「自由」, for acting on one's own initiative 「自発的」. The opposites are 「強制」 and 「義務」.

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

1. 束縛そくばくや制限せいげんがなく自分じぶんの思おもうがままであること。