The term "tosses off" refers to doing something quickly or casually, often without particular care or attention. Antonyms for this phrase could include terms such as "deliberate," "meticulous," or "thoughtful." These opposite terms suggest a different approach to tasks or actions, one that involves taking one's time and carefully considering each step. For instance, the antonym "meticulous" implies a focus on details and a desire to do things thoroughly and accurately, rather than just "tossing them off" haphazardly. Other antonyms might include terms like "serious," "conscientious," or "slow," all of which suggest a more measured and thoughtful approach to tasks.