Definitions

1. adjective

most likely to inform on or betray the trust of others, especially in an illegal or disapproved activity

“He’s been acting snitchiest since his brother got arrested.”

2. noun

the most likely to inform on or betray the trust of others, especially in an illegal or disapproved activity

“The snitchiest kid in school always tattled on his friends.”

3. superlative form of snitchy

having or showing the quality of being a snitch or informant, especially in an illegal or disapproved activity

“The snitchiest player on the team got caught cheating.”