What's the difference: 楽観的 vs のんき


Both these words seem to mean "worry-free" or optimistic. A quick
[check](https://thesaurus.weblio.jp/content/%E6%A5%BD%E8%A6%B3%E7%9A%84%E3%81%AB%E8%A6%8B%E3%82%8B)
on Weblio somehow validates this. How do these words differ in terms of
nuance? のんき is also said to mean
[careless](https://tangorin.com/definition/%E3%81%AE%E3%82%93%E3%81%8D) and
other things that have a negative connotation in English, but I cannot see
sample sentences that support these negative qualities (unlike, say,
[そそっかしい](https://tangorin.com/definition/%E3%81%9D%E3%81%9D%E3%81%A3%E3%81%8B%E3%81%97%E3%81%84)).




のんき is about temper. A のんきな人 is always calm (often to a fault), slow to start
doing something, and rarely gets serious/angry. The antonym is 短気 (short-
tempered) or せわしい (restless).

楽観的 is about one's way of thinking. A 楽観的な人 is an optimistic person who
believes "It's gonna be okay". The antonym is 悲観的 (pessimistic). You can use
楽観的 to describe your attitude about one specific issue. For example,
私はこの件に関して楽観的です means "I am optimistic about this issue". 楽観的 does not
necessarily modify a person/personality. You can say 楽観的な予測 "optimistic
estimate", for example.




のんき is about temper. A のんきな人 is always calm (often to a fault), slow to start
doing something, and rarely gets serious/angry. The antonym is 短気 (short-
tempered) or せわしい (restless).

楽観的 is about one's way of thinking. A 楽観的な人 is an optimistic person who
believes "It's gonna be okay". The antonym is 悲観的 (pessimistic). You can use
楽観的 to describe your attitude about one specific issue. For example,
私はこの件に関して楽観的です means "I am optimistic about this issue". 楽観的 does not
necessarily modify a person/personality. You can say 楽観的な予測 "optimistic
estimate", for example.

