There are various words that can be used as synonyms for the phrase "beat painfully". Some examples include "pummel", "thrash", "hammer", "batter", and "bash". All of these words suggest a forceful and repeated striking action, often resulting in pain or injury. Other synonyms may include "smack", "whack", "slap", or "punch", depending on the type of beating being described. It's important to choose an appropriate synonym for the context of the sentence in order to accurately convey the severity of the beating. Regardless, all of these words describe a violent and aggressive action that can lead to serious harm or injury.