自発的|じはつてきjihatsuteki

1. na-adjectivespontaneous; voluntary
   彼かれは自発的じはつてきに降伏こうふくした。↗

   He surrendered of his own accord.

• Synonym自主的じしゅてきNeutralEmphasizes acting on one's own authority, free of outside interference; 自発的 stresses doing things of one's own accord. The two are often interchangeable.
• Related随意ずいいWrittenWritten word for acting freely, without restrictions, as in 「随意に」「ご随意に」; 自発的 stresses doing something willingly and on one's own initiative.
• Related任意にんいNeutralMeans it is up to you whether to do something, as in 「任意参加」; also used for choosing any at random. 自発的 stresses one's own active willingness.
• Related意欲的いよくてきNeutralHighlights eager, energetic engagement, as in 「意欲的な作品」; 自発的 stresses acting without being asked or told to.
• Related随意的ずいいてきWrittenFormal term for choosing freely by one's own will, mostly in technical contexts such as 「随意筋」; everyday speech prefers 「任意」 or 「自由」.
• Antonym強制的きょうせいてきNeutralMaking someone do something against their will; the direct opposite of 自発的, which is acting of one's own accord.
• Antonym受動的じゅどうてきWrittenWritten word for passively receiving things and acting only when prompted by others; contrasts with the active stance of 自発的.

Use 「自発的」 for doing something of your own accord; 「自主的」 when the point is acting independently, and the two often swap. 「任意」 covers things you are free to do or skip; 「随意」 is its written counterpart. Antonyms: 「強制的」 (forced) and 「受動的」 (passive).

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

1. 自みずから進すすんで物事ものごとを行おこなう様よう。
2. 自然しぜん発生はっせい的てきに起おこる様さま。