"Fierce resistance" means a strong and determined opposition or fight, where people or things aggressively defend against an opposing force or idea. Full definition
Any move towards burning more plastic waste, though, would be met with fierce resistance from environmental groups. (bbc.com)
A government plan to push for an upper limit of 5,000 euros to cash payments was met with fierce resistance two years ago, including by the country's own central bank. (cnbc.com)
But she draws fierce resistance over changes such as closing schools and laying off counselors, clerical workers and other staff even as she gives raises to her leadership team. (chicagotribune.com)