There are many different words that can be used as synonyms for "watches for". Some common options include "monitors", "observes", "keeps an eye on", "tracks", "follows", "witnesses", and "surveys". Depending on the context and intended meaning, certain synonyms may be more appropriate than others. For example, "monitors" might be best used in a medical or technological setting, while "follows" could be more fitting in a detective story or sports commentary. Ultimately, the most effective synonym will be one that accurately conveys the desired meaning in the given context.