용 (yong) (用) means "to use" and is a very common root in Korean. However grasping the small differences in meaning between the different words that use 용 can be quite tricky. Here's a small list with some explanations. The Korean words given in parenthesis after the definition are words that share the same chinese root as the defined word.



이용
이롭게 씀
to profit from, to employ well, to take advantage of

사용
물건을 씀
사람 따위를 부림.
to use things. to employ people

이용 and 사용 are probably the two more common words on this list especially in their verbal "-하다" form (사용하다, 이용하다). They're usually both translated as to use, although it seems that 이용하다 conveys an idea of profit which is not implied by 사용하다.

고용
품삯을 주고 사람을 부림
to employ and give wages to someone

공용
공적으로 씀
to use in common. for public use. (공공: public)

과용
지나치게 씀
to use excessively (과다: excess)

관용
관습적으로 쓰는 것
something used customarily. (관습: custom)

군용
군사 목적에 쓰이는 것
something used with a military objective (군사: military)

무용
to be useless

대용
대신으로 씀
to use instead of something (대신: instead)

시용
시험적으로 써 봄
to use as a trial (시험: trial, test)

실용
실제로 씀
to use practically (실제: practice)

외용
먹거나 주사하지 않고 몸의 겉에 씀
to use on the surface on the body instead of ingesting or injecting.
= to use externally (medical)

유용
쓸모가 있음
to be useful (쓸모: usefulness)