Prophylactically is an adjective that describes actions taken to prevent disease or infection. Synonyms for this word include preventative, precautionary, preemptive, anticipatory, and pre-empting. These words all describe actions taken in advance to avoid negative outcomes. Other synonyms for prophylactically include protective, preservative, shielding, and defensive. These words suggest a sense of safety and security, and describe actions taken to keep something from being harmed. Overall, there are many words that can be used as synonyms for prophylactically, each with their own unique connotations and implications.