1. Very uncertain
   "left everything up in the air" 
2. Not yet determined
   "plans are still up in the air"

See also: uncertain

• cockspur thorn
• cocksucker
• cocksure
• cocksureness
• cocktail
• cocktail dress
• cocktail lounge
• cocktail party
• cocktail sauce
• cocktail shaker
• cocktail stick
• cocktail table
• cockup
• cocky
• cocky-leeky
• coco
• coco de macao
• coco palm
• cinnamon fern
• cinnamon roll
• cinnamon snail
• cinnamon stone
• cinnamon toast
• cinnamon vine
• cinnamon-colored