FactorList[poly] gives a list of the factors of a polynomial, together with their exponents.
ImageAssemble[{{image_11, image_12, ...}, {image_21, ...}, ...}] assembles a single image from an array of images.
InitializationGroup is an option for the first cell of a cell group that specifies whether the group should be tagged to be evaluated by the Mathematica kernel when the ...
KroneckerDelta[n_1, n_2, ...] gives the Kronecker delta \[Delta] Subscript[n, 1] Subscript[n, 2] ..., equal to 1 if all the n_i are equal, and 0 otherwise.
MatrixForm[list] prints with the elements of list arranged in a regular array.
MessagePacket[symbol, string] is a MathLink packet containing a Mathematica message identifier of the form symbol::string.
NumberPoint is an option for NumberForm and related functions which gives the string to use as a decimal point.
Order
(Built-in Mathematica Symbol) Order[expr_1, expr_2] gives 1 if expr_1 is before expr_2 in canonical order, and -1 if expr_1 is after expr_2 in canonical order. It gives 0 if expr_1 is identical to expr_2.
Path
(Built-in Mathematica Symbol) Path is an option for Get and related functions which gives a list of directories to search in attempting to find an external file.
Plain
(Built-in Mathematica Symbol) Plain represents a font that is not bold, italic, or underlined.