(superlative of bad) of the poorest quality or lowest standard; worse than any other person or thing of a similar kind It was by far the worst speech he had ever made. What's the worst thing that could happen? What she said confirmed my worst fears (= proved they were right).
Idioms to be the cause of your own problems Her indecisiveness makes her her own worst enemy. See worst in the Oxford Advanced Learner's DictionaryCheck pronunciation:
worst