がるTo feel, To think, To act as if, To want, To desire

がる is a う-Verb that is primarily used as a suffix in Japanese. When used in this way, it means 'to act like (A)', or 'to show signs of being (A)', where (A) is the word that it is attached to.

To use がる, you will need to link it to the stem form of an い-Adjective (simply remove the い), or to the stem form of a な-Adjective (do not include the な).

がる is a verb which means 'to give the impression of (A)', or 'to act like (A)'. This is very important in Japanese, as you would not usually say how somebody else feels, unless they told you directly and you are simply repeating what you heard (in which case you would use the quotation particle と).

When you want to express the way you 'think' that someone else feels, but don't have any direct information about it, that is when がる would be natural to use. For example, if you see someone shivering in the cold, you would say something like the following.

The main difference between がる, and がっている, is that がる will be used when a person usually/always acts a certain way, whereas がっている is more about the way someone/something is acting in any specific moment.