embolus
noun /ˈembələs/
  /ˈembələs/
(plural emboli 
 (medical) /ˈembəlaɪ/,  /ˈembəliː/
  /ˈembəlaɪ/,  /ˈembəliː/
)- a blood clot, air bubble, or small object that causes an embolismWord Originmid 17th cent. (denoting something inserted or moving within another, specifically the plunger of a syringe): from Latin, literally ‘piston’, from Greek embolos ‘peg, stopper’. The current sense dates from the mid 19th cent.