1. The state of being variable, different, divergent, or deviate; a degree of deviation. 2. A measure of the variation shown by a set of observations, defined as the sum of squares of deviations from the mean, divided by the number of degrees of freedom in the set of observations.
ball v. swelling and changes in shape and consistency of the ball in a ball-valve prosthesis, especially in one replacing the aortic valve.
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