AnimationRate is an option for Animate and Animator that specifies at what rate an animation should run, in units per second.
AutoSpacing is an option for Style and Cell that specifies whether spaces between successive characters should be adjusted automatically.
Baseline is a symbol that represents the baseline for purposes of alignment and positioning.
Beep
(Built-in Mathematica Symbol) Beep[] generates an audible beep when evaluated.
Bottom
(Built-in Mathematica Symbol) Bottom is a symbol that represents the bottom for purposes of alignment and positioning.
CellGrouping is a notebook option that specifies how cells in the notebook should be assembled into groups.
CircleMinus[x, y] displays as x\[CircleMinus]y.
ClearSystemCache[] clears internal system caches of stored results.
Deletable is an option for Cell that specifies whether the cell can be deleted interactively using the front end.
DeleteDirectory["dir"] deletes the specified directory.