Indeed, although I recognize EasterJoy’s point – yet in fact many sources describe the Kyrie not as “retained” but, indeed, as injected into the Roman rite. The Catholic Encyclopedia
says:
Its introduction into the Roman Mass has been much discussed. It is certain that the liturgy at the Rome was at one time said in Greek (to the end of the second century apparently). It is tempting to look upon our Kyrie Eleison as a surviving fragment from that time. Such, however, does not seem to be the case. Rather the form was borrowed from the East and introduced into the Latin Mass later.
It is mostly
Latin (habeas corpus, de minimis, malum prohibitum, etc.) and
mediaeval French (plaintiff, bailiff, tort, voir dire, etc.). Both are the result of the Norman Conquest.