More sacred, spiritual, or morally pure than someone else; also used sarcastically to mean more self-righteously superior.
Comparative form of holy, from Old English halig meaning 'whole, uninjured, sacred.' The word originally meant whole or unbroken, and the spiritual sense developed because wholeness was associated with spiritual perfection.
The phrase 'holier-than-thou' describes people acting superior, but linguistically it's interesting that 'holy' started as 'whole'—the idea that spiritual purity was like being complete and unbroken.
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