na-adjective, noun
Expresses sympathy or compassion for someone in a sad or unfortunate situation. Often used in the phrase 不憫に思う (to feel sorry for).
彼の境遇を不憫に思う。
I feel sorry for his circumstances.
あの子は親がいなくて不憫だ。
That child is pitiful, having no parents.
Rarely used kanji form; easily confused with 不便 (ふべん, 'inconvenient').
かわいそう is more common in everyday speech and carries a stronger emotional tone of pity. 不憫 is slightly more literary and often used in writing or formal contexts.
哀れ can also mean 'pitiful' but often implies a deeper sense of sorrow or tragedy, and can be used for things as well as people. 不憫 is more focused on feeling sorry for a person's situation.
The word is composed of 不 (not) and 憫 (compassion/pity), literally meaning 'without compassion', but it is used to describe someone who is pitiable. The exact historical derivation is uncertain.