noun
optimist; easy-going person
Describes a person who habitually looks on the bright side and does not worry much. Often carries a positive, light-hearted tone.
彼はどんな状況でも前向きな楽天家だ。
He is an optimist who stays positive in any situation.
楽天家の彼女は、
Being an easy-going person, she quickly bounces back even after a failure.
Antonym: a pessimist. 楽天家 is the opposite in everyday usage.
Compound of 楽天 (optimism, from 楽 'comfort' and 天 'heaven') and 家 (person with a certain trait). The exact historical derivation is uncertain, but the word has been used since the Meiji era to describe a person with an optimistic nature.