There are various synonyms for the phrase "criticizing severely" that can be used to express disapproval or condemnation of someone or something. Some of the words that carry a similar meaning are denounce, condemn, castigate, lambaste, berate, rebuke, censure, reproach, admonish, chastise, vilify, and excoriate. Each of these words represents a different level of severity, with some being stronger than the others. However, all of them imply a negative or harsh judgment of someone or something. As such, it is vital to use these words with tact and caution to avoid causing offense or hurting someone's feelings unnecessarily.