Verbseoul.
ㄹ stem (adj)
가늘다ganeuldato be thin, to be slender

To say to be thin, to be slender politely in the present tense, use 가늘어요 (gah-neu-ruh-yoh). Below is the full conjugation of 가늘다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
가늘어
gah-neu-ruh
가늘어요
gah-neu-ruh-yoh
가늡니다
gah-neum-nee-dah
Past
가늘었어
gah-neu-ruh-ssuh
가늘었어요
gah-neu-ruh-ssuh-yoh
가늘었습니다
gah-neu-ruh-sseum-nee-dah
Future
가늘 거야
gah-neul- -guh-yah
가늘 거예요
gah-neul- -guh-yae-yoh
가늘 겁니다
gah-neul- -guhm-nee-dah

Other useful forms

Command Polite (세요)
가느세요
gah-neu-sae-yoh
Suggestion / Let's Polite (요)
가늘어요
gah-neu-ruh-yoh
Question Polite (요)
가늘어요?
gah-neu-ruh-yoh-?
Connective “and” — (고)
가늘고
gah-neul-goh
Conditional “if” — (면)
가늘면
gah-neul-myuhn
Noun form — (기)
가늚
gah-neum