1.Definition: a person who does something thoughtless or annoying

"Some joker is blocking the driveway"

Related Noun(s):turkey

Category: People

2.Definition: a person who enjoys telling or playing jokes

Related Noun(s):jokester

Category: People

3.Definition: a playing card that is usually printed with a picture of a jester

Category: Objects

4.Definition: an inconspicuous clause in a document or bill that affects its meaning in a way that is not immediately apparent

"When I demanded my money he showed me the joker in the contract"

Category: General