The most overused word is "literally".
The word "literally" originally meant that something occurs in a strict and factual sense, although the word literally now is casually and even ironically used as an everyday emphasis for exaggerations or even metaphors.
For example, someone saying, I was literally dying of laughter at what happened to him.
Other overused words include.
Like.
Awesome and Amazing.
Synergy.
Thought leader.
Revolutionary.
And even gaslight and luxury.