The phrase "catch at straws" means to grasp at any available opportunity or hope in a desperate situation. Its antonyms would, therefore, be words that denote a lack or absence of hope or opportunity. These could include words like "abandonment," "defeat," "resignation," or "giving up." Other antonyms for "catch at straws" could be phrases like "face reality," "accept the inevitable," "concede a loss," or "relinquish false hope." It is important to note that while "catch at straws" implies a sense of desperation, its antonyms do not necessarily indicate a sense of defeat or surrender. Instead, they suggest a more realistic and pragmatic approach to a difficult situation.