* Companion: Shares the root of "company" and refers to someone you keep company with.
* Companionship: The state or quality of being a companion.
* Company man/woman: A person who is very loyal to their company, often to the detriment of other priorities. (This is an idiomatic phrase, not a true derivative.)
* Companies (plural): This is a straightforward derivative showing multiple companies.
While there aren't many formal derivations like "-ation" or "-ment" suffixes producing new words, the semantic connections to words like "companion" and phrases like "company man" show how the word's meaning branches out.