신고자가 · 신고자를
person who reports (to police or authorities), informant, caller
Example
경찰은 신고자의 신분을 철저히 보호합니다.
Police strictly protect the identity of people who report crimes.
Word parts
신 report+고 tell+자 person
-자 = person who does it: 신고자 'one who reports', 운전자, 과학자.
Related words