To lambaste is to reprimand or berate someone severely. People lambaste those who have angered or disappointed them.
Have you ever watched a basketball game and noticed a coach yelling like a maniac at a referee? That coach is lambasting the referee. Lambasting is also called chewing out, taking to task, scolding, reprimanding, berating, bawling out, and chiding. Parents lambaste disobedient kids. A boss might lambaste a worker who is late all the time. Lambasting is severe and goes way beyond criticizing. When you are lambasting, you are furious at someone and letting them know it.