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

• Lexulous
• Wordscraper
• Wordosaur

n. A person who is neither clearly extroverted nor introverted, but has characteristics of each.

"An ambivert sounds like a cross between ambivalent and pervert, but it's someone who has both extrovert and introvert personality traits."

ambiversion