Plural of 'drab': dull grayish-brown colors, or people/things lacking in liveliness or color.
From 'drab' (noun) plus the regular plural suffix '-s'. Drab as a noun refers to the color itself, from uncertain origins but possibly Low German/Dutch textile terminology.
In fashion history, drabs were the default—most common people wore drabs because that's what wool looked like undyed, which means 'drab' literally comes from the default color of human poverty.
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