“You have my word.”

An alternative world where everyone is defined by tangible words that appeared with them at birth (hovering over their heads, tattooed on their bodies, or in another way you can choose). These words, usually adjectives or nouns describing personality and lifestyle, are different depending on a person's spoken language(s) and dialect. Normally, people have no control over what their words say... until a breakthrough in science/magic changes this.

The story begins with an event (human-made plague, explosion, evil ritual, take your pick) causing people's words to disappear, turning them into mindless zombies. Can we rewrite what has already been erased and stop the world from going silent?