Verbseoul.
하다 verb (adj)
불가피하다bulgapihadainevitable, unavoidable

To say inevitable, unavoidable politely in the present tense, use 불가피해요 (bool-gah-pee-hae-yoh). Below is the full conjugation of 불가피하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
불가피해
bool-gah-pee-hae
불가피해요
bool-gah-pee-hae-yoh
불가피합니다
bool-gah-pee-hahm-nee-dah
Past
불가피했어
bool-gah-pee-hae-ssuh
불가피했어요
bool-gah-pee-hae-ssuh-yoh
불가피했습니다
bool-gah-pee-hae-sseum-nee-dah
Future
불가피할 거야
bool-gah-pee-hahl- -guh-yah
불가피할 거예요
bool-gah-pee-hahl- -guh-yae-yoh
불가피할 겁니다
bool-gah-pee-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
불가피하세요
bool-gah-pee-hah-sae-yoh
Suggestion / Let's Polite (요)
불가피해요
bool-gah-pee-hae-yoh
Question Polite (요)
불가피해요?
bool-gah-pee-hae-yoh-?
Connective “and” — (고)
불가피하고
bool-gah-pee-hah-goh
Conditional “if” — (면)
불가피하면
bool-gah-pee-hah-myuhn
Noun form — (기)
불가피함
bool-gah-pee-hahm