Checkbox[x] represents a checkbox with setting x, displayed as CheckboxBox[True] when x is True and CheckboxBox[False] when x is False. Checkbox[Dynamic[x]] takes the setting ...
Dashing
(Built-in Mathematica Symbol) Dashing[{r_1, r_2, ...}] is a two-dimensional graphics directive specifying that lines that follow are to be drawn dashed, with successive segments of lengths r_1, r_2, ... ...
DensityPlot[f, {x, x_min, x_max}, {y, y_min, y_max}] makes a density plot of f as a function of x and y.
Erfc
(Built-in Mathematica Symbol) Erfc[z] gives the complementary error function erfc(z).
HarmonicNumber[n] gives the n\[Null]^th harmonic number H_n. HarmonicNumber[n, r] gives the harmonic number H_n^(r) of order r.
Indeterminate is a symbol that represents a numerical quantity whose magnitude cannot be determined.
ItemStyle is an option for Grid, Column, and related constructs that specifies styles to use for items.
LegendreQ[n, z] gives the Legendre function of the second kind Q_n (z). LegendreQ[n, m, z] gives the associated Legendre function of the second kind Q_n^m(z).
MapAt
(Built-in Mathematica Symbol) MapAt[f, expr, n] applies f to the element at position n in expr. If n is negative, the position is counted from the end. MapAt[f, expr, {i, j, ...}] applies f to the part of ...
Mod
(Built-in Mathematica Symbol) Mod[m, n] gives the remainder on division of m by n. Mod[m, n, d] uses an offset d.