A companion is someone who spends time with you, sharing experiences and keeping you company. Your best friend who sits with you at lunch every day is your companion. A hiking companion walks the trail beside you. When astronauts spend months together on a space station, they become each other's closest companions.

The word suggests actively sharing experiences together. A true companion participates in what's happening with you. The person sitting next to you on the bus isn't necessarily your companion, but if you strike up a conversation and chat the whole ride, they can become one.

Animals can be companions too. Dogs have been human companions for thousands of years, and we often call them companion animals because they share our daily lives, offering loyalty and friendship.