항의해요 · 항의했어요 · 항의할 거예요 · 항의하세요
to protest, complain (formally)
Example
손님이 서비스가 나쁘다고 매니저에게 항의했어요.
The customer complained to the manager about the bad service.
Word parts
항 oppose+의 discuss
Literally 'argue in opposition'.
Good to know
Use 에게/에 for the target: 회사에 항의하다; 시위 is a street protest, 항의 is any complaint.