half in jest; partly for fun; capricious
Describes doing something not entirely seriously, often with a playful or whimsical motive. Commonly used in the adverbial form 慰み半分に.
He started writing a novel half for fun.
A remark made half in jest hurt her feelings.
Compound of 慰み (なぐさみ, 'comfort, amusement') and 半分 (はんぶん, 'half'). The exact historical derivation is uncertain, but the word literally suggests doing something 'half for amusement'.