Actio
Actio a word frequently used to designate the canon of the mass. Taken from the word agere, which bears in classical writers the special sense of performing a sacrificial act, the word action is applied to that which was regarded as the essential portion of the eucharistic sacrifice. Whatever is included in the canon is said to be infra actionem. Hence, when any words are to be added within the canon, as at great festivals, they bear in the liturgies the title, or rubric, infra-actionem; and in printed missals these words are frequently placed before the prayer Communicantes.
