WordNet (r) 3.0 (2006):

Word of God
    n 1: a manifestation of the mind and will of God
    2: the sacred writings of the Christian religions; "he went to
       carry the Word to the heathen" [syn: Bible, Christian
       Bible, Book, Good Book, Holy Scripture, Holy Writ,
       Scripture, Word of God, Word]
    3: the message of the Gospel of Christ

Easton's 1897 Bible Dictionary:

Word of God
   (Heb. 4:12, etc.). The Bible so called because the writers of
   its several books were God's organs in communicating his will to
   men. It is his "word," because he speaks to us in its sacred
   pages. Whatever the inspired writers here declare to be true and
   binding upon us, God declares to be true and binding. This word
   is infallible, because written under the guidance of the Holy
   Spirit, and therefore free from all error of fact or doctrine or
   precept. (See INSPIRATION; BIBLE.) All
   saving knowledge is obtained from the word of God. In the case
   of adults it is an indispensable means of salvation, and is
   efficacious thereunto by the gracious influence of the Holy
   Spirit (John 17:17; 2 Tim. 3:15, 16; 1 Pet. 1:23).