informant

An informant is someone who secretly provides information to police, the FBI, or another law enforcement agency. If you watch a lot of crime shows on TV, you're probably familiar with informants.

In the world of law enforcement, informants are officially called CIs, for "confidential informant" or "criminal informant." The information informants provide can be useful in catching criminals, and the informant usually gets something in return — money or a reduced prison sentence, for example. Sometimes informant simply means "person who gives information."

Definitions of informant
1

n a person who supplies information

Synonyms:
source
Types:
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betrayer, blabber, informer, rat, squealer
one who reveals confidential information in return for money
leaker
a surreptitious informant
passive source
an informant who is not assigned to obtain specific intelligence but who routinely passes on whatever information he or she has
whistle blower, whistle-blower, whistleblower
an informant who exposes wrongdoing within an organization in the hope of stopping it
canary, fink, sneak, sneaker, snitch, snitcher, stool pigeon, stoolie, stoolpigeon
someone acting as an informer or decoy for the police
copper's nark, nark
an informer or spy working for the police
grass, supergrass
a police informer who implicates many people
Type of:
communicator
a person who communicates with others

n someone who sees an event and reports what happened

Synonyms:
witness, witnesser
Types:
attestant, attester
someone who affirms or vouches for the correctness or truth or genuineness of something
deponent, deposer, testifier
a person who testifies or gives a deposition
Type of:
beholder, observer, perceiver, percipient
a person who becomes aware (of things or events) through the senses
speaker, talker, utterer, verbaliser, verbalizer
someone who expresses in language; someone who talks (especially someone who delivers a public speech or someone especially garrulous)

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