Coproduct[x, y, ...] displays as x\[Coproduct]y\[Coproduct]....
CorrelationDistance[u, v] gives the correlation coefficient distance between vectors u and v.
CounterStyleMenuListing is an option for cells that specifies what counter styles are listed in the Counter popup menu of the Create Automatic Numbering Object dialog box.
CovarianceEstimatorFunction is an option for generalized linear model fitting functions that specifies the estimator for the parameter covariance matrix.
DateDifference[date_1, date_2] gives the number of days from date_1 to date_2.DateDifference[date_1, date_2, " unit"] gives the difference between date_1 and date_2 in the ...
DefaultDuration is an option to Animate and related functions that specifies the default total duration of the animation in seconds.
DialogProlog is an option for Dialog that can give an expression to evaluate before the dialog starts.
Directory[] gives the current working directory.
DoubleBracketingBar[x, y, ...] displays as \[LeftDoubleBracketingBar]x, y, ...\[RightDoubleBracketingBar].
DoubleLeftArrow[x, y, ...] displays as x \[DoubleLeftArrow] y \[DoubleLeftArrow] ....