* Formal: My grandmother's faithful companion, a small terrier named Buttons, never left her side.
* Informal: I brought a good book to the beach as a companion for my afternoon of sunbathing.
* Descriptive: The lone traveler found solace in the silent companionship of the mountains.
* Figurative: Music is my constant companion, a source of joy and solace.
* Specific: The guide was a knowledgeable and friendly companion for our hike.