FileExistsQ["name"] gives True if the file with the specified name exists, and gives False otherwise.
GeoDestination[pos, {d, \[Alpha]}] gives the geodetic position reached by going distance d in azimuthal direction \[Alpha] from pos.
GridGraph[{m, n}] gives the grid graph with m*n vertices G m, n.GridGraph[{n_1, n_2, ..., n_k}] gives the k-dimensional grid graph with n_1*n_2*\[CenterEllipsis]*n_k vertices ...
IgnoreCase is an option for string manipulation and searching functions that specifies whether lowercase and uppercase letters should be treated as equivalent.
ImageReflect[image] reverses image by top-bottom mirror reflection. ImageReflect[image, side] reverses image by reflecting it so that the specified side goes to the opposite ...
InputAliases is an option for cells and notebooks which specifies additional Esc\[ThinSpace]name\[ThinSpace]Esc aliases to be allowed on input.
Khinchin is Khinchin's constant, with numerical value \[TildeEqual] 2.68545.
Large
(Built-in Mathematica Symbol) Large is a style or option setting that specifies that objects should be large.
LibraryLoad[lib] loads the dynamic library lib into the Mathematica runtime.
MathieuGroupM24[] represents the sporadic simple Mathieu group M_24.