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

• Lexulous
• Wordscraper
• Wordosaur

adj. In a state of fossilization; preserved in rock.

adj. Converted into a fossil; antiquated; firmly fixed in views or opinions.

adj. set in a rigidly conventional pattern of behavior, habits, or beliefs

"Morse, on the other hand, does not enjoy such a "bench" of highly-visible, "all-star" contributors in one case, the Yahoo organization has been characterized as "fossilized", yet, to be fair, he is also not expected to be a "magician.""

inflexible   

antiquated   

fossilize