worst-case scenario adverb 1noun 1forms 2 adverb1 •(informal) At worst, worst comes to worst, in the worst-case scenario.I'll get the ends of my hair dyed. Worst-case scenario, I can cut them off. noun1 •Any situation or conclusion which could not be any worse; the worst possible outcome.Everyone is rightly planning for the worst-case scenario. Across Europe, that worst-case scenario is already playing out. — 2020 formsworst case scenarios · worst-case scenarios