SpellingDictionariesPath is a global option that specifies which directories are searched for spelling dictionaries when the Edit \[FilledRightTriangle] Check Spelling menu ...
SubStar
(Built-in Mathematica Symbol) SubStar[expr] displays as expr_*.
SystemHelpPath is a global option that specifies which directories are searched for the help notebooks used within the help system.
Tiny
(Built-in Mathematica Symbol) Tiny is a style or option setting that specifies that objects should be tiny.
TitsGroupT[] represents the simple Tits group T.
Trigger
(Built-in Mathematica Symbol) Trigger[Dynamic[u]] represents a trigger that can be pressed to make the dynamically updated value of u be continually increased with time from 0 to 1. Trigger[Dynamic[u], ...
WindowFrameElements is an option for notebooks that specifies the elements to include in the frame of the window used to display the notebook on the screen.
$Failed
(Built-in Mathematica Symbol) $Failed is a special symbol returned by certain functions when they cannot do what they were asked to do.
$InstallationDirectory gives the top-level directory in which your Mathematica installation resides.
$LicenseExpirationDate is a date list that gives the expiration date for the license under which Mathematica is being run.