참 + adjective; 참! = Oh, right! (remembering)
really, truly, very; oh right
Example
오늘은 하늘이 참 맑고 예쁘네요.
The sky is really clear and pretty today.
Word parts
Also a native noun meaning 'truth', as in 참말 'true words'.
Good to know
Said alone, 참! means 'Oh, right!' when you suddenly remember something.
Related words