Count
(Built-in Mathematica Symbol) Count[list, pattern] gives the number of elements in list that match pattern. Count[expr, pattern, levelspec] gives the total number of subexpressions matching pattern that ...
DegreeGraphDistribution[dlist] represents a degree graph distribution with vertex degree dlist.
DGaussianWavelet[] represents a derivative of Gaussian wavelet of derivative order 2.DGaussianWavelet[n] represents a derivative of Gaussian wavelet of derivative order n.
Dialog
(Built-in Mathematica Symbol) Dialog[] initiates a dialog. Dialog[expr] initiates a dialog with expr as the current value of %.
DialogNotebook[{cell_1, cell_2, ...}] represents a dialog notebook that can be manipulated by the Mathematica front end.
DirectedEdges is an option for Graph, GraphPlot, and related functions that specifies whether edges should be taken to be directed.
Evaluate[expr] causes expr to be evaluated even if it appears as the argument of a function whose attributes specify that it should be held unevaluated.
ExclusionsStyle is an option to plotting functions that specifies how to render subregions excluded according to Exclusions.
ExpandDenominator[expr] expands out products and powers that appear as denominators in expr.
FactorSquareFree[poly] pulls out any multiple factors in a polynomial.