願望・意志N4
〜がる
feels... (third person, shown outwardly)
Structure
い形容詞（語幹）/ な形容詞（語幹）/ たい + がる
Explanation
Attached to adjectives of emotion or sensation (い-adjectives minus い, な-adjective stems, 〜たい forms, etc.), 〜がる expresses feelings of a third person that are observable from the outside, e.g. 怖がる, 嬉しがる, 行きたがる. Conjugates as a godan (u-verb) pattern.
Examples
うちの猫はお風呂を嫌がります。
Our cat dislikes taking baths.
子供は新しいおもちゃをもらって、とても喜んでいました。
The child was very happy to receive a new toy.
Note
Adjectives of emotion cannot directly describe a third person's inner state; use 〜がる. 〜たがる is a special combination of たい + がる.