This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

ad. In a peripheral manner.

ad. At or towards a periphery.

On or from the periphery or exterior surface; as regards the periphery: as, peripherally acting inhibitory nerves.

ad. in or at or near a periphery or according to a peripheral role or function or relationship

"What most folks understand only peripherally is that the way we view children’s fairy tales, and the way that the world of the fey was considered in the past, are two very different animals."