1. Lacking brightness or colour; dull
   "children in sombre brown clothes"
   - drab, sober, somber [US] 
2. Grave or even gloomy in character
   "a suit of sombre black"; "a sombre mood"
   - somber [US], melancholy

See also: cheerless, colorless [US], colourless [Brit, Cdn], depressing, sombreness, uncheerful

Encyclopedia: Sombre

• Cooper Union for the Advancement of Science and Art
• Cooper's hawk
• cooperage
• cooperate
• cooperation
• cooperative
• cooperatively
• cooperativeness
• cooperator
• Cooperstown
• coordinate
• coordinate axis
• coordinate bond
• coordinate clause
• coordinate geometry
• coordinate system
• coordinated
• coordinated universal time
• coordinately
• coordinating
• coordinating conjunction
• coordination
• coordination compound
• coordinative
• coordinator