It's a past participle of the verb "best", which is often used in a formal or literary context.
Here are some examples of how "bested" can be used:
* "The knight was bested by the dragon in battle."
* "The new design bested the old one in terms of efficiency."
* "He felt bested by the eloquent arguments of his opponent."
It's important to note that "bested" can also imply being outwitted or outmaneuvered, not just defeated in a physical sense.