Indeterminate is a symbol that represents a numerical quantity whose magnitude cannot be determined.
InverseEllipticNomeQ[q] gives the parameter m corresponding to the nome q in an elliptic function.
JacobiSC[u, m] gives the Jacobi elliptic function sc(u | m).
JacobiZeta[\[Phi], m] gives the Jacobi zeta function Z(\[Phi] \[VerticalSeparator] m).
KleinInvariantJ[\[Tau]] gives the Klein invariant modular elliptic function J(\[Tau]).
Nearest
(Built-in Mathematica Symbol) Nearest[{elem_1, elem_2, ...}, x] gives the list of elem_i to which x is nearest. Nearest[{elem_1 -> v_1, elem_2 -> v_2, ...}, x] gives the v_i corresponding to the elem_i to ...
SinIntegral[z] gives the sine integral function Si(z).
Speak
(Built-in Mathematica Symbol) Speak[expr] speaks a spoken representation of the expression expr.
StringCases["string", patt] gives a list of the substrings in " string" that match the string expression patt. StringCases["string", lhs -> rhs] gives a list of the values of ...
StringReplace["string", s -> sp] or StringReplace["string", {s_1 -> sp_1, s_2 -> sp_2, ...}] replaces the string expressions s_i by sp_i whenever they appear as substrings of ...