Here's why and some alternatives:
* "Possess" is a verb, not an adjective: Adverbs modify verbs, adjectives, or other adverbs. "Possess" is an action word.
* We use other words to convey the idea of "possessing" in an adverbial way:
* "Posssessively" is an adverb describing how something is possessed, often with a strong sense of ownership.
* "Possessively" can be used like this: "She held her new puppy possessively."
* Other adverbs like "proudly," "securely," "jealously," "eagerly," etc., can be used depending on the context.
For example:
* "He held the ancient artifact securely." (The adverb "securely" describes how he held it, suggesting possession.)
* "She looked at her new car proudly." (The adverb "proudly" suggests a feeling of possession.)
Let me know if you have a specific sentence in mind and I can help you choose the best adverb!