Well, 'exactly' right back at'cha! But don't reduce the meaning of the "Word of God" just to what's between the covers of the Bible. That would be un-Biblical, because the Bible itself instructs us, as St. Paul says, to "stand firm and hold to the traditions which you were taught by us, either by word of mouth or by letter" (2 Thess. 2:15).
This oral teaching was accepted by Christians, just as they accepted the written teaching. Jesus told his disciples: "He who hears you hears me, and he who rejects you rejects me" (Luke 10:16).
This "hearing" means, precisely, oral instruction: "So faith comes from what is heard, and what is heard comes by the preaching of Christ" (Rom. 10:17). The Church would always be the living teacher. So it is a mistake to limit "Christ’s word" to only His written word.
God teaches us also by Natural Law--- created by His Word --- and the Church is the guide and interpreter of all this truth, whether from the Book of Nature or the Book of Scripture.
In Scripture, we have everything we need to be "complete, thoroughly equipped for every good work" (2 Timothy 3:17).