The terminology of form and matter to describe the sacraments seems to have been first proposed by William of Auxerre.
However, the Catholic Encyclopedia states this conceptual view of the sacraments was already present in Augustine of Hippo's writings.
[1] The Catechism of the Council of Trent explains this concept this way: "every Sacrament consists of two things; 'matter,' which is called the element, and 'form,' which is commonly called 'the word.
This matter is administered to a recipient along with the accompanying form, which is the Latin sentence "Ego te baptizo in nomine Patris, et Filii, et Spiritus Sancti", with the person pronouncing those words doing so with the proper intention.
[1][5] On 3 February 2024, the Dicastery for the Doctrine of the Faith released a note approved by Pope Francis named Gestis verbisque.