Answer:
These words are in Latin, I believe, and when they are translated to English they mean:
- Kyrie: Lord
- Gloria: Glory
- Credo: I believe that (I think this word is also related to the Apostles' Creed)
- Sanctus: St. (Saint)
- Agnus Dei: Lamb of God
This was one of the two categories of the Roman Mass, called the Ordinary of the Mass.
(the other is called the Proper of the Mass) Mentioned above were the five standard prayers of this Mass 'Ordinary', and these prayers were sang.
Hope I helped :)
