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1.
To manipulate the truth using words and actions, with the intent of crafting the perception of others to your benefit.

It often has the appearance of, "playing dumb," or "bad luck".

It is not the individual occurrence that defines it, but the long-term pattern. "The truth is what I say it is."
Examples:

1. "Saying there is no such thing as 'emotional adultery' is just gamesmanship. You know you cannot have friends of the opposite sex without some kind of approval from me, as you would expect!"

2. "Your honor, it is gamesmanship for the State to deny my Work Comp, because they have failed to give me a legitimate hearing and they entertain a conflict of interest since it is there own money they are protecting."
by Reasonable2014 February 14, 2014