Source : Webster's Revised Unabridged Dictionary (1913)

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).