(excessively or hypocritically pious) "a sickening sanctimonious smile"
: hypocritically pious or devout <a sanctimonious moralist><the king's sanctimonious rebuke — G. B. Shaw>
obsolete : possessing sanctity : holy
— sanc·ti·mo·nious·ly adverb
— sanc·ti·mo·nious·ness noun
Pronunciation: Sanc as in sanctuary. Ti as in tit, or Ti mothy. Mon sounds like moan, rhymes with phone. I rhymes with tree. Ous sounds the same as it does in glorious.
holier-than-thou, pietistic, pietistical, pharisaic, pharisaical, self-righteous
I find it interesting that the word was used to mean close to the opposite of what it does now. Lesss confusing than constellate, anyway.