Verbseoul.
하다 verb (adj)
잔인하다janinhadato be cruel

To say to be cruel politely in the present tense, use 잔인해요 (chah-neen-hae-yoh). Below is the full conjugation of 잔인하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
잔인해
chah-neen-hae
잔인해요
chah-neen-hae-yoh
잔인합니다
chah-neen-hahm-nee-dah
Past
잔인했어
chah-neen-hae-ssuh
잔인했어요
chah-neen-hae-ssuh-yoh
잔인했습니다
chah-neen-hae-sseum-nee-dah
Future
잔인할 거야
chah-neen-hahl- -guh-yah
잔인할 거예요
chah-neen-hahl- -guh-yae-yoh
잔인할 겁니다
chah-neen-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
잔인하세요
chah-neen-hah-sae-yoh
Suggestion / Let's Polite (요)
잔인해요
chah-neen-hae-yoh
Question Polite (요)
잔인해요?
chah-neen-hae-yoh-?
Connective “and” — (고)
잔인하고
chah-neen-hah-goh
Conditional “if” — (면)
잔인하면
chah-neen-hah-myuhn
Noun form — (기)
잔인함
chah-neen-hahm