Possibly means that something might happen or might be true, but you're not certain. When your teacher says the field trip will possibly be on Friday, she means it could happen then, but the plans aren't final yet. When you tell your friend you'll possibly come to their birthday party, you're saying there's a chance you'll make it, but you can't promise.

The word sits in the middle ground between “definitely” and “no way.” If someone asks whether it might rain tomorrow, answering possibly means you think there's a real chance, even if it's not certain. Scientists use this word carefully when they're not ready to make strong claims: “This fossil possibly belongs to a new species” means they see evidence pointing that way, but need more proof.

Possibly often appears when people are being honest about uncertainty rather than pretending to know more than they do. When you say “I possibly left my homework at home,” you're admitting you're not sure where it is. The word can also express polite doubt, like when you say “That's possibly true” about something that sounds questionable. Using possibly shows you understand the difference between what you know for certain and what might be true.