1. Not explained
   "accomplished by some unexplained process" 
2. Having the reason or cause not made clear
   "an unexplained error"

See also: incomprehensible, inexplicable, undetermined

Encyclopedia: Unexplained

• football team
• football tee
• football-shaped
• footballer
• footbath
• footboard
• footbridge
• footcandle
• footed
• footedness
• footer
• footfall
• footfault
• footgear
• foothill
• foothold
• footie
• footing
• footle
• footless
• footlights
• footling
• footlocker
• footloose
• footman