Technically speaking, a “sacramentary” is a very particular book. Wikipedia actually has a rather decent explanation:
The Sacramentary is a book of the Middle Ages containing the words spoken by the priest celebrating a Mass and other church services. The books were usually in fact written for bishops or other higher clegy such as abbots, and many lavishly decorated illuminated manuscript sacramentaries have survived.
Though in the late twentieth century the word “sacramentary” was used in the United States and other English-speaking countries for the English translation of the Roman Missal, a true sacramentary is not the same as a Missal. It contains more than a missal in terms of other services, and less in that texts and readings said by others during the Mass are not included.
It is the book for the priest celebrant, containing all and only the words spoken (or sung) by him, usually assuming the presence of a choir and deacon. At the time that these books were written it was not yet the custom for the celebrant to repeat at the altar whatever was sung by the ministers or the choir, as became the rule in the Tridentine Mass. The one exception to this rule was the Gospel, which in the Tridentine Mass the priest listens to when sung by the deacon, instead of at the same time reading it quietly for himself, as he does with the Epistle when sung by the subdeacon. Thus Sacramentaries contain none of those parts of the Mass, not only no Scripture readings, but also no Introits, Graduals, Offertories and so on, but only the Collects, Prefaces, Canon.
On the other hand sacramentaries provide the priest’s texts at other occasions besides Mass. As they suppose that the celebrant is normally a bishop, they usually supply the texts for ordinations, at the consecration of a church and altar and many exorcisms, blessings, and consecrations that were later inserted in the Pontifical and Ritual.
So, to clarify: the book out of which the Mass is prayed is the
Missale Romanum, the “Roman Missal”. The English translation of the modern form of the Roman Rite (i.e. the Ordinary Form, the Missal of Paul VI, the Novus Ordo, etc.) was called – by ICEL, I imagine – the “Sacramentary” instead of the “Roman Missal”. While Rome permitted this for several years, when it came time for the English translation of the third edition of the modern Roman Missal, Rome made the decision that
Missale Romanum should be rendered in English as “Roman Missal”:
The word “Sacramentary”, evidently chosen to distinguish this book containing the prayers of the Mass, on the one hand, from the Lectionary, on the other, seems nevertheless to have had the adverse effect of furthering a mistaken conception of this “Sacramentary” as a new and somewhat autonomous liturgical book for the English-speaking world. The term “Sacramentary” is not characterized by a linear historical development, and the present book also contains antiphons and other elements that were not in the ancient or medieval books commonly designated sacramentaries, at least in academic usage.
Accordingly, the Congregation asks that from now on the book be referred to in English as The Roman Missal, and that the official use of the word Sacramentary be discontinued in reference to it. (
source)