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

• Lexulous
• Wordscraper
• Wordosaur

adj. comparative form of holy: more holy; more sacred.

adj. comparative form of holey: more holey; more full of holes.

"Mr. Anderson was also bugged by what he describes as the holier-than-thou attitude typified by Critical Mass, a monthly gathering of bikers who coast through the city, snarling traffic for hours."

holier-than-thou   

lovelier    inmost    loftier    lambent    airier    profounder    true    kindlier    sacerdotal    sacredest