PrivatePaths -> {opt_1 -> val_1, opt_2 -> val_2, ...} is a global option that specifies settings for paths private to the notebook front end.
RevolutionAxis is an option for RevolutionPlot3D which specifies the revolution axis around which the curve should be rotated.
SelectedNotebook[] gives the currently selected notebook in the front end.
StartScheduledTask[obj] starts the task represented by obj.
TextJustification is an option for Cell and Inset which specifies how much lines of text can be stretched in order to make them be the same length.
TopologicalSort[g] gives a list of vertices of g in topologically sorted order for a directed acyclic graph g.
TraceDialog[expr] initiates a dialog for every expression used in the evaluation of expr. TraceDialog[expr, form] initiates a dialog only for expressions which match form. ...
UnderoverscriptBox[x, y, z] is the low-level box representation for x_y^z in notebook expressions.
UnderscriptBox[x, y] is the low-level box representation for UnderscriptBox[x, y] in notebook expressions.
Uninstall[link] terminates an external program started by Install, and removes Mathematica definitions set up by it.