As nouns the difference between stop and stillness
is that
stop is a (usually marked) place where line buses, trams or trains halt to let passengers get on and off, usually smaller than a station while
stillness is the quality or state of being still; quietness; silence; calmness; inactivity.
As a verb stop
is to cease moving.
As an adverb stop
is prone to halting or hesitation.
As an interjection stop
is halt! stop.