Abstemii is a Roman Catholic term used to identify those who could not parpake of the eucharist (communion) within the Roman Catholic Church. This has to do with a belief or conviction within these people against taking strong drink.
An abstemius (plural abstemii) is one who cannot takewine without risk of vomiting. As, therefore, the consecration at Mass must be effected in both species, of bread and wine, an abstemius is consequently irregular.
St. Alphonsus Liguori, following the opinion of Suarez, teaches that such irregularity is de jure divino (Latin: “of divine law”); and that, therefore, the Pope cannot dispense from it. The term is also applied to one who has a strong distaste for wine, though able to take a small quantity. A distaste of this nature does not constitute irregularity, but a papal dispensation is required, in order to excuse from the use of wine at the purification of the chalice and the ablution of the priest’s fingers at the end of a Mass celebrated in the Tridentine Mass. In these cases the use of wine is a canonical law from whose observance the Church has power to dispense. A decree of the Sacred Congregation for the Propagation of the Faith, dated 13 January 1665, grants a dispensation in this sense to missionaries in China, on account of the scarcity of wine; various similar rulings are to be found in the collection of the decrees of the Sacred Congregation of Rites. Wikipedia.org
ABSTEMII. A name given to such persons as could not partake of the cup of the eucharist, on account of their natural aversion to wine.