I suppose that, while I was at it, I should have cited Chytraeus’ general definition of a sacramentum as well, in order to indicate how he construes such rites in broader terms. So here it is (it has the advantage of being brief):
Quid est sacramentum?
SACRAMENTUM, est actio sacra, a Deo instituta, constans verbo et administratione elementi integri, et addita promissioni, quae est Evangelij propria, ut promissionem gratiae singulis applicet, et fidem in viventibus obsignet et confirmet.
What is a sacrament?
A sacrament is a sacred action, instituted by God, consisting of the Word and the administration of a complete element, and added to the promise that is proper to the Gospel, in order to apply the promise of grace to individuals and to seal and strengthen faith in them while they are alive. 1
So, it is: (1) an action; (2) of divine institution; it has (3) two components (Word and administration); it is (4) added to the promise that already exists in the Gospel of God’s grace and forgiveness to those who believe; and (5) it is instituted with the purpose of applying that promise to particular people (namely, to those who believe, as is clear from the next clause), and of sealing and strengthening their faith in that promise while on their earthly pilgrimage.