Russian-English translations for невзначай

• by accident
  Sorry. I knocked over the vase by accident.
  The car got totaled by accident; a giant snowdrift fell off the church roof.
  The only way that project still exists today is by accident; I thought we closed it years ago.
• by chance
  I stumbled across the exit by chance.
  Are you by chance looking for the exit?
• inadvertently
• unexpectedly