Definitions

1. adjective

most difficult to deceive or cheat; most cunning or deceitful

“He was considered the trickiest salesman in the company.”

2. adjective

most difficult to deal with or overcome; most cunning or skillful

“The new traffic system proved to be the trickiest part of the city.”

3. noun

a person or thing that is the most cunning or skillful

“She was the trickiest opponent in the chess tournament.”