Formal:
* Lexicographer: This is the most formal term, referring to someone who compiles dictionaries. While they don't always create new words, they often research and document existing ones.
* Neologist: This term specifically refers to someone who creates new words.
* Etymologist: While primarily concerned with the history and origin of words, they might also contribute to the creation of new words, especially when analyzing historical usage.
Informal:
* Wordsmith: This is a general term for someone who is skilled in using words, and it can include those who create new words.
* Inventor: While not specifically tied to language, this could be used in a playful sense for someone who creates new words.
* Linguist: While linguists primarily study language, some might be involved in the creation of new terminology or jargon within specific fields.
Ultimately, the best word will depend on the specific context and the type of word creation being discussed.