unsmiling (adj.)

• cheerless
• decorous
• demure
• discontented
• earnest
• formal
• frowning
• grave
• grim
• humorless
• joyless
• long-faced
• mirthless
• miserable
• sedate
• serious
• sober
• sobersided
• solemn
• somber
• sorry
• staid
• thoughtful
• uncheerful
• unhappy
• weighty
• wretched