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

See also: uncertain

• photosynthesis
• photosynthesise
• photosynthesize
• photosynthetic
• phototaxis
• phototherapy
• phototrophic bacteria
• phototropic
• phototropic bacteria
• phototropism
• photovoltaic
• photovoltaic cell
• Phoxinus
• Phoxinus phoxinus
• PHP
• phragmacone
• Phragmipedium
• Phragmites
• Phragmites communis
• phragmocone
• phrasal
• phrasal idiom
• phrasal verb
• phrase
• phrase book