면구스러워요 · 면구스러웠어요 · 면구스러운 (+noun) (ㅂ irregular)
to be ashamed, embarrassed (to face someone)
Example
도와주신 분께 연락을 못 드려서 면구스러워요.
I feel ashamed that I never got in touch with the person who helped me.
Word parts
면 face+구 burn
Hanja suggest a face that burns, as with shame; rather old-fashioned today.