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

• Lexulous
• Wordscraper
• Wordosaur

adj. Marked by interest in or preoccupation with oneself or one's own thoughts as opposed to others or the environment; shy or reserved.

adj. Possessing the characteristic property of an introvert. Preferring the internal, satisfied with self, lacking interest or comfort in social interactions.

adj. examining one's own sensory and perceptual experiences. Contrasted with extrospective.

adj. marked by concern predominantly with oneself or one's own feelings. Contrasted with extroverted.

adj. given to examining own sensory and perceptual experiences

"Gadhafi was known as an introverted, somewhat arrogant figure who read more books than the other officers and insisted on the ideas he learned in their pages."

introspective   

introvert