suffix, godan verb (-ru)
show signs of feeling; seem to feel; want to
Attaches to the stem of adjectives (and some nouns) to express that someone appears to feel that way or shows outward signs of that state. Often used for third-person emotions or desires, since Japanese adjectives normally describe the speaker's own feelings.
彼は新しいおもちゃを欲しがっている。
He is showing signs of wanting the new toy.
犬が寒がって震え
The dog is shivering, seeming to feel cold.
suffix, godan verb (-ru)
act as if one is; pretend to be; put on airs of
Attaches to adjective stems or nouns to describe someone behaving as if they possess that quality, often with a negative or critical nuance of putting on airs. The cross-reference 得意がる (to act proud) is a typical example.
See also: 得意がる (とくいがる)
彼は偉がって、いつも命令口調だ。
He acts all high and mighty and always speaks in a commanding tone.
あの人は金持ちがっているけど、本当は借金だらけらしい。
That person acts like they're rich, but I hear they're actually deep in debt.