DocumentNotebook[{cell_1, cell_2, ...}] represents a complete document notebook in the Mathematica front end.
DownValues[f] gives a list of transformation rules corresponding to all downvalues defined for the symbol f.
Dt
(Built-in Mathematica Symbol) Dt[f, x] gives the total derivative d f/d x. Dt[f] gives the total differential d f. Dt[f, {x, n}] gives the multiple derivative d^n f/d x^n. Dt[f, x_1, x_2, ...] gives d/d ...
DumpSave["file.mx", symbol] writes definitions associated with a symbol to a file in internal Mathematica format. DumpSave["file.mx", " context`"] writes out definitions ...
DynamicModule[{x, y, ...}, expr] represents an object which maintains the same local instance of the symbols x, y, ... in the course of all evaluations of Dynamic objects in ...
EdgeForm[g] is a graphics directive which specifies that edges of polygons and other filled graphics objects are to be drawn using the graphics directive or list of ...
EdgeRenderingFunction is an option for GraphPlot and related functions that gives a function to generate the graphics primitives to use in rendering each edge.
EllipticExp[u, {a, b}] is the inverse for EllipticLog. It produces a list {x, y} such that u == EllipticLog[{x, y}, {a, b}].
E
(Built-in Mathematica Symbol) E is the exponential constant E (base of natural logarithms), with numerical value \[TildeEqual] 2.71828.
EulerGamma is Euler's constant \[Gamma], with numerical value \[TildeEqual] 0.577216.