"joker" in the noun sense
1. joker, jokester
a person who enjoys telling or playing jokes
2. joker, turkey
a person who does something thoughtless or annoying
"some joker is blocking the driveway"
3. joker
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"
4. joker
a playing card that is usually printed with a picture of a jester
Source: WordNet® (An amazing lexical database of English)
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