In colloquial terms, a sharp tongue is often used to describe an individual who speaks harshly, critically or in a manner that can come off as abrasive or rude. Some synonyms for this phrase could include blunt, cutting, acerbic, biting, caustic, and sarcastic. Other phrases that could be used to describe this kind of behavior include acidic wit, acid-tongued, or venomous speech. It is important to note that while the tongue may be sharp and the words may sting, it is possible to learn how to communicate assertively without resorting to belittling or attacking others.