caustic - Dictionary definition and meaning for word caustic
caustic soda is very common and its "harmful " for health if taken in large quantity....therefore caustic means harmful or burning. Since its a soda its somehow related with chemistry as well..
In medical terms 'cauterize' is burning or sealing the ends of blood vessels/nerves similar to destroying; As far as speech, talking about the holoCAUST can be harsh
caustic=it CAUSes your TIssues destroy!
The stinging sunburn I got CAUSed an involuntary TICk in my arm.