Toxic hemoglobinuria is a medical condition where the destruction of red blood cells leads to the release of toxic substances, causing damage to the kidneys and leading to dark urine. There are a few antonyms for this condition, which means words that have opposite meanings. One of these antonyms is "healthy," which means unaffected by illness or injury, without any toxic substances in the blood. Another antonym is "normal," which refers to a state of health and well-being without any abnormality, damage, or toxic substances present. Finally, "non-toxic" is another antonym, meaning free from any harmful, poisonous, or toxic substances.