Adjective dark blue has 1 sense
  1. blue, bluish, blueish, light-blue, dark-blue, blue-black - having a color similar to that of a clear unclouded sky; "October's bright blue weather"- Helen Hunt Jackson; "a blue flame"; "blue haze of tobacco smoke"
    Antonym: achromatic (indirect, via chromatic)
,Noun dark blue has 1 sense
  1. dark blue, navy, navy blue - a dark shade of blue
    --1 is a kind of blue, blueness
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