A product of the "Voice" of the Presence, the Word is said to have been created when the Presence first spoke.
The Word's primary mission in life seemed to be to battle things that challenged the power of the Presence. When Swamp Thing began to his quest to unite the elemental forces of Earth the Word decided he was a threat.
Before engaging Swamp Thing the Word killed the elemental Parliaments of Earth. He then attacked Swamp Thing when the elemental was at his weakest, having been temporarily turned into a human by John Constantine. However, Tefé Holland came to her father's defense, transforming herself into a giant mystical voice-box that was able to generate sound waves that imitated the sounds of the Voice. She was able to generate counter-soundwaves that cancelled out the sounds of the divine words that the Word was composed of, bringing his visible form to nothing.
Exerpt from Scribblenauts Unmasked: A divine being, the Word is a manifestation of the God's truth in visible form.