There are several synonyms for the phrase "knocks over". One such word is "topples", which means to fall or overbalance. Another alternative is "upsets", which implies the act of overturning or turning something upside down. "Capsizes" is another apt synonym, particularly with regards to boats, ships, or other water vessels being turned over. "Overturns" and "overthrows" are also commonly used to describe the act of knocking over something, especially objects like chairs, tables or shelves. Lastly, "tumbles" or "falls" are also popular synonyms, particularly when referring to small items knocked over by accident. Whatever the synonym used, they all describe the act of something being knocked down or over.