As verbs: "Counter" means to oppose something in some way. This depends a lot on context. For example, in arguments (law, debate, etc.) to counter is to express an opposite view from that of your opponent. Whereas in video games and card games, to counter is to respond to someone's attack with your own attack. "Encounter" means to meet. It can refer to meeting people, things, or situations. As nouns: "Counter" usually refers to a type of long table-type surface. For example "kitchen counter". Google image search the word to better understand this. It can also refer to any machine (mechanical or digital) that is used to count things. An "encounter" is a meeting and is often used in a negative or at least ambiguous/complex sense, since a friendly meeting can just be called a "meeting" or "get-together".