1. A lexicographer of new words and expressions or a person who coins or makes up new words.
2. Someone who invents or employs new words.
3. Anyone who introduces, or uses new words, or new senses of existing words.
4. A person who adopts new views, or new doctrines; especially, a new interpretation of sacred writings or views of theology.
5. In psychiatry, someone who produces a new word, often consisting of a combination of other words, that is understood only by the speaker.

This occurs most often in the speech of schizophrenics.