DefaultMenuStyle is a low-level option for menu-generating constructs that specifies the default style to use for displaying menu items.
DefaultNaturalLanguage is an option for character selections that specifies the language used when checking the spelling of a word in a human natural language selection.
Default
(Built-in Mathematica Symbol) Default[f] gives the default value for arguments of the function f obtained with a _. pattern object. Default[f, i] gives the default value to use when _. appears as the ...
DefaultNewCellStyle is a notebook option which specifies the default style to use for new cells created in the notebook.
DefaultNewInlineCellStyle is an option for cells that specifies the default style to use for new inline cells created in the notebook.
DefaultNotebook is a global option that specifies which notebook is used as a template for all new notebooks.
DefaultOptions is a style option that allows default options to be specified for particular formatting and related constructs.
DefaultStyleDefinitions is a global option that specifies the default stylesheet for all new notebooks.
DefaultTicksStyle is a low-level option for graphics functions that specifies the default style to use in rendering ticks.
Defer
(Built-in Mathematica Symbol) Defer[expr] yields an object that displays as the unevaluated form of expr, but that is evaluated if it is explicitly given as Mathematica input.