drab

Drab probably traces back to Middle French and Old French drap, meaning 'cloth,' itself from Late Latin drappus or a Frankish word for fulled fabric. But the noun sense in English is uncertain, and some scholars instead connect it to Middle English words for soiling or dragging through mud, and to Old Norse drabba, 'to make dirty.'

The word likely began as a name for a plain, undyed woolen cloth, and from there slid toward describing its dull grayish-brown color — eventually coming to mean dullness or dreariness in general.

It may be a distant cousin of drop, if the sediment-and-dirt origin holds true, linking drab's dinginess to the idea of something settling or falling.