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

See also: uncertain

• tissue plasminogen activator
• tissue typing
• tit
• tit for tat
• tit-tat-toe
• titan
• titan arum
• titanate
• Titaness
• titania
• titanic
• titanic acid
• titanic oxide
• titaniferous
• titanium
• titanium dioxide
• titanium oxide
• titanosaur
• titanosaurian
• Titanosauridae
• Titanosaurus
• titbit
• titch
• titchy
• titer