Acerbo : 1 . Rough to taste. 2 , Cruel, rigorous, unpleasant , says the RAE . Some synonyms, words or similar expressions can be harsh2 , spicy, sour, acrid2 , sour , bitter cruel , ruthless , tasteless , unpleasant , unpleasant , harsh , relentless , rough , rigorous , austere , severe , says the rae