In Korean, adjectives operate as ‘descriptive verbs‘ and they can be conjugated into different tenses like the way typical verbs are.
But first, you need to know that there are 3 word forms in Korean: Dictionary form, Written form, Spoken form.
Dictionary form :
~다, word entry that you see in a dictionary. ex) 바쁘다 = to be busy
The part of the word preceding 다 is called the “word stem“.
Adjective form used in written Korean such as books, newspapers and etc.
ex) 바쁘다 = to be busy : Please make sure that the dictionary form and the casual written form are the same. For adjectives, we use a dictionary form as a casual written form. However, in verbs, there are separate dictionary forms and written forms.
ex) * 바쁩니다, polite = to be busy
: Polite adjectives can be also used in polite speech. For instance you’ll hear a news reporter using polite adjectives in their speech.
Adjective form used in spoken Korean
ex) 바빠요, **casual polite = to be busy