from
The Collaborative International Dictionary of English v.0.48
Filioque \Fil`i*o"que\, n. (Eccl. Hist.)
The Latin for, "and from the Son," equivalent to et filio,
inserted by the third council of Toledo (a. d. 589) in the
clause qui ex Patre procedit (who proceedeth from the Father)
of the Niceno-Constantinopolitan Creed (a. d. 381), which
makes a creed state that the Holy Ghost proceeds from the Son
as well as from the Father. Hence, the doctrine itself (not
admitted by the Eastern Church).
[Webster 1913 Suppl.]