GeometricMean[list] gives the geometric mean of the values in list.
GoldenRatio is the golden ratio \[Phi] = 1/2 (Sqrt[5] + 1), with numerical value \[TildeEqual] 1.61803.
GraphDistanceMatrix[g] gives the matrix of distances between vertices for the graph g.GraphDistanceMatrix[g, d] gives the matrix of distances between vertices of maximal ...
GraphHighlightStyle is an option to Graph and related objects that specifies styles to use for highlighted graph elements.
GraphRadius[g] gives the minimum eccentricity of the vertices in the graph g.
GridBox
(Built-in Mathematica Symbol) GridBox[{{box_11, box_12, ...}, {box_21, box_22, ...}, ...}] is a low-level box construct that represents a two-dimensional grid of boxes or strings in notebook expressions.
GroupSetwiseStabilizer[group, {p_1, ..., p_n}] returns the subgroup of group for which the images of the points p_i are still in the list {p_1, ..., p_n}.
HankelH1[n, z] gives the Hankel function of the first kind H_n^(1)(z).
HankelH2[n, z] gives the Hankel function of the second kind H_n^(2)(z).
HarmonicMean[list] gives the harmonic mean of the values in list.