1. Not easy to believe
   "behind you the coastal hills plunge to the incredibly blue sea backed by the Turkish mountains"
   - improbably, implausibly, unbelievably 
2. Exceedingly; extremely
   - fabulously, fantastically

See also: incredible

Antonym: credibly

• breathing time
• breathless
• breathlessly
• breathlessness
• breathtaking
• breathtakingly
• breathy
• breccia
• brecciate
• Brecht
• brede
• breech
• breech birth
• breech closer
• breech delivery
• breech presentation
• breech-loading
• breechblock
• breechcloth
• breechclout
• breeched
• breeches
• breeches buoy
• breeching
• breechloader