명 Adjective
관형사 immediately precede a 체언 and do not decline. There are only a few in Korean.
You can modify verbs to create a 관형사 by using a 관형사형 전성 어미.
Not that 형용사 (Adjective Verbs) are not to be confused with 관형사. 형용사 are 용언 (Verb) and require an 어미 (Verb Ending).
