'darkish' originates from Modern English, specifically the adjective 'dark' combined with the suffix '-ish', where 'dark' meant 'without light' and '-ish' meant 'having the quality of' or 'somewhat like'.

'dark' changed from the Old English word 'deorc' (also spelled 'derk') and evolved through Middle English into the modern form 'dark'; the suffix '-ish' comes from Old English '-isc' and Proto-Germanic '-iskaz' and was attached to form 'darkish'.

Initially, 'dark' primarily meant 'without light' or 'obscure'; over time the combination with '-ish' produced 'darkish', meaning 'somewhat dark' or 'slightly resembling darkness', with extended figurative senses of gloominess.