(Latin: and the Son)
A word that briefly recalls the Catholic doctrine which insists, against Greek Schismatics, that the Holy Ghost proceeds from the Father and the Son, as from one principle, and by one act of love.
The Greeks first objected to its insertion in the Nicene Creed, as though against the discipline enjoined by the Council of Ephesus (431), and later as they drifted into schism under Photius (c.870), they challenged the doctrine, and denied the procession of the Holy Ghost from the Son.
The "Filioque," which expresses the ancient Christian tradition of even the Greek Fathers, first crept into the Nicene Creed in the liturgy of Spain, in the 6th century, and gradually prevailed in Western Christianity as the official and liturgical expression of the revealed truth, that the Holy Ghost proceeds at once from the Father and the Son, as He is the Spirit of the Son as well as the Father.
New Catholic Dictionary