One who plots or schemes, who formulates plans.(noun)
One who is given to scheming.(noun)
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Use "schemer" in a sentence
"Tennyson was also known as a schemer and operator."
"Then to be called a schemer before the class and to be pandied when he always got the card for first or second and was the leader of the Yorkists!"
"Her reward for playing the "sexism card" was relentless grilling by some members of the all-male Judiciary Committee and being characterized as a schemer, a vixen, a liar and a tramp."