のんき・呑気・暢気・暖気nonki[1]atamadaka (head-high)

1. na-adjective, nouneasy; easygoing; carefree; happy-go-lucky; optimistic; leisurely; careless; thoughtless
   お前まえは当事者とうじしゃじゃないから、そんなのんきなこと言いってられるんだよ。↗

   You wouldn't be so casual about it if you were directly involved.

• Synonym気楽きらくNeutralFree of stress and at ease, as in 「気楽な一人暮らし」; 「呑気」 adds a nuance of carelessness.
• Synonym楽天的らくてんてきNeutralNaturally optimistic and cheerful — a matter of personality; it doesn't itself imply carelessness, but taken too far it can sound critical.
• Synonym屈託のないくったくのないNeutralA phrase for having no worries at all — innocent and cheerful, as in 「屈託のない笑顔」; carries an approving tone.
• Synonym安気あんきNeutralDescribes a peaceful, relaxed state of mind; it sounds old-fashioned and is seldom used in modern Japanese.
• Related楽観的らっかんてきNeutralTakes an optimistic view of the future — a matter of judgment; 「呑気」 instead describes a leisurely, easygoing nature.
• Related楽チンらくチンCasualColloquial: easy and effortless, or physically comfortable, as in 「楽チンな靴」「楽チンな仕事」; applies to both things and tasks.
• Related屈託ないくったくないNeutralCarefree, with no worries or reservations; synonymous with 「屈託のない」.

Use 「呑気」 for an easygoing, worry-free air that can shade into carelessness, as in 「呑気な人」. For feeling relaxed and unburdened pick 「気楽」; for innocent cheerfulness 「屈託のない」; for optimism 「楽観的」 or 「楽天的」.

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

1. 気晴きばらし。
2. 気楽きらくなこと。また、そのようなさま。
3. 気きが長ながいこと。