Resembling, relating to, or characteristic of heathens; uncivilized, irreligious, or barbaric in a way associated with non-Christian peoples.
From 'heathen' plus the suffix '-ish' (Old English '-isc'), which means 'somewhat like' or 'of the nature of.' This adjectival form has been used since at least the 15th century to describe things perceived as uncivilized or non-Christian.
The suffix '-ish' is fascinating because it's gentler than '-ish' applied to other concepts—'heathenish' sounds almost affectionate compared to how harsh 'heathen' itself feels, yet historically it was used derogatorily to dismiss entire civilizations.
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