The word 'transsubstancjacja' appears to be a misspelling or a non-English variant of the term 'transubstantiation.' In English, 'transubstantiation' refers to the doctrine in the Roman Catholic Church that during the Eucharist, the substances of bread and wine are transformed into the actual body and blood of Christ, while their appearances remain unchanged. noun
During the Mass, the priest spoke about the mystery of transubstantiation.
The doctrine of transubstantiation is central to Catholic belief in the Eucharist.