'un-Moorish' originates from English, specifically the negative prefix 'un-' combined with the adjective 'Moorish' ('Moor' + suffix '-ish'), where 'un-' meant 'not' and '-ish' formed adjectives meaning 'having the quality of'.

'Moorish' developed from 'Moor' (from Old French more, from Latin 'Maurus', originally referring to inhabitants of Mauretania and later to Muslim inhabitants of northwest Africa and Iberia) plus the Old English/Old Germanic adjectival suffix '-isc'/'-ish'. The modern compound 'un-Moorish' is a productive negation formed in Modern English by prefixing 'un-' to that adjective.

Initially 'Moor' referred to people from Mauretania and then broadly to Muslim inhabitants of parts of North Africa and Iberia; 'Moorish' came to mean 'relating to those people or their architectural/style traditions'. Over time the negative formation 'un-Moorish' has come to mean 'not exhibiting those Moorish characteristics'.