IPA: /ɪnˈfɔːrmər/
KK: /ɪnˈfɔrmər/
A person who provides information, especially about someone else's wrongdoing, often for a reward.
The police relied on an informer to gather information about the criminal activities in the area.
Informer → It is formed from "in-" (meaning in or into) and "formare" (meaning to shape or form). The word "informer" refers to someone who shapes or provides information, often to authorities.
Think of someone who brings information 'into' ('in-') a situation, helping to 'shape' ('formare') understanding or action.