DefaultButton[] represents an OK button that closes a dialog, and is the default when DynamicBox[ToBoxes[If[$OperatingSystem === "MacOSX", "Return", "Enter"], StandardForm], ...
DependentVariables is an option which specifies the list of all objects that should be considered as dependent variables in equations that have been supplied.
Diagonal[m] gives the list of elements on the leading diagonal of the matrix m.Diagonal[m, k] gives the elements on the k\[Null]^th diagonal of m.
Dilation[image, ker] gives the morphological dilation of image with respect to the structuring element ker.Dilation[image, r] gives the dilation with respect to a range r ...
DirichletConvolve[f, g, n, m] gives the Dirichlet convolution of the expressions f and g.
DynamicWrapper[e, expr] represents an object that displays as e, but dynamically updates the expression expr whenever that object is visible on screen.
EdgeDelete[g, e] makes a graph by deleting the edge e from the graph g.EdgeDelete[g, {e_1, e_2, ...}] deletes a collection of edges from g.EdgeDelete[g, patt] deletes all ...
Erosion
(Built-in Mathematica Symbol) Erosion[image, ker] gives the morphological erosion of image with respect to the structuring element ker.Erosion[image, r] gives the erosion with respect to a range-r square.
EvenQ
(Built-in Mathematica Symbol) EvenQ[expr] gives True if expr is an even integer, and False otherwise.
ExtractArchive[file] expands an archive file, saving its content into the current directory.ExtractArchive[file, dir] saves the content of an archive file into directory ...