Verbseoul.
하다 verb (adj)
그윽하다geueukhadato be mellow, to be subtle

To say to be mellow, to be subtle politely in the present tense, use 그윽해요 (geu-eu-kae-yoh). Below is the full conjugation of 그윽하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
그윽해
geu-eu-kae
그윽해요
geu-eu-kae-yoh
그윽합니다
geu-eu-kahm-nee-dah
Past
그윽했어
geu-eu-kae-ssuh
그윽했어요
geu-eu-kae-ssuh-yoh
그윽했습니다
geu-eu-kae-sseum-nee-dah
Future
그윽할 거야
geu-eu-kahl- -guh-yah
그윽할 거예요
geu-eu-kahl- -guh-yae-yoh
그윽할 겁니다
geu-eu-kahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
그윽하세요
geu-eu-kah-sae-yoh
Suggestion / Let's Polite (요)
그윽해요
geu-eu-kae-yoh
Question Polite (요)
그윽해요?
geu-eu-kae-yoh-?
Connective “and” — (고)
그윽하고
geu-eu-kah-goh
Conditional “if” — (면)
그윽하면
geu-eu-kah-myuhn
Noun form — (기)
그윽함
geu-eu-kahm