The term 'harsh or corrosive in tone' can be summarized by two crossword solutions: CAUSTIC (7 letters) and ACRID (5 letters). CAUSTIC refers to something that is very sharp or biting, often used to describe a person's words or behavior. ACRID, on the other hand, is used to describe an unpleasant smell or taste that is strong and pungent. Both terms are often used to describe a situation or person that is unpleasantly harsh or corrosive in tone.