Nafcillin is an antibiotic that is used to treat serious bacterial infections. However, if you need to find alternative words for nafcillin, there are a few options available. One possible synonym for nafcillin is dicloxacillin, which is also an antibiotic that is used to treat bacterial infections. Another synonym for nafcillin is methicillin, which is another antibiotic that is similar in structure and function. Additionally, oxacillin is another synonym for nafcillin, which is also an antibiotic that is used to treat bacterial infections. Regardless of which synonym you use, it is always important to follow your doctor's instructions and take all medication as prescribed.