BooleanVariables[expr] gives a list of the Boolean variables in the Boolean expression expr.BooleanVariables[bf] gives the number of Boolean variables in the BooleanFunction ...
BoxMatrix[r] gives a (2 r + 1)*(2 r + 1) matrix of 1s.BoxMatrix[r, w] gives a (2 r + 1)*(2 r + 1) block of 1s centered in a w*w matrix of 0s.BoxMatrix[{r_1, r_2, ...}, ...] ...
BoxRatios is an option for Graphics3D that gives the ratios of side lengths for the bounding box of the three-dimensional picture.
Break
(Built-in Mathematica Symbol) Break[] exits the nearest enclosing Do, For, or While.
ButtonBox[boxes] is a low-level box construct that represents a button in a notebook expression.
CanberraDistance[u, v] gives the Canberra distance between vectors u and v.
CayleyGraph[group] returns a Cayley graph representation of group.
CDFInformation[expr] gives a list of properties relevant to a CDF deployed with the content expr.CDFInformation[notebook] gives usage properties for a CDF to be deployed from ...
CellContext is an option for Cell which specifies the context to use for the evaluation of the contents of the cell.
CellDingbat is an option for Cell which specifies what dingbat to use to emphasize a cell.