tran ‧ sub ‧ stan ‧ ti ‧ a ‧ tion /ˌtrænsəbstænʃiˈeɪʃ ə n/ BrE AmE noun [uncountable]
[ Date: 1300-1400 ; Language: Medieval Latin ; Origin: transubstantiatio , from transubstantiare 'to change into another substance' , from Latin substantia 'substance' ]
the belief of some Christians that the bread and wine taken in Holy Communion become the actual body and blood of Christ