1. In an exhaustive manner
   "we searched the files thoroughly"
   - exhaustively 
2. Completely and absolutely ('good' is sometimes used informally for 'thoroughly')
   - soundly, good

See also: thorough

• icebox
• icebox cake
• icebreaker
• icecap
• icecream
• iced coffee
• iced tea
• iced-tea spoon
• icefall
• icehouse
• Iceland
• Iceland lichen
• Iceland moss
• Iceland poppy
• Iceland spar
• Icelander
• Icelandic
• Icelandic krona
• Icelandic monetary unit
• Icelandic-speaking
• iceman
• icepick
• icetray
• ichneumon
• ichneumon fly