What is the name of someone who uses long words?

There isn't a single, commonly accepted word for someone who uses long words. However, here are some options depending on the context and your intended meaning:

Neutral:

* Eloquent: This suggests someone who uses language effectively and powerfully, often with complex vocabulary.

* Learned: This implies someone with extensive knowledge and a wide vocabulary.

* Erudite: Similar to "learned," this suggests someone deeply knowledgeable and scholarly.

Negative:

* Pompous: This implies someone who uses long words to show off their intelligence or importance, rather than to communicate effectively.

* Pretentious: Similar to "pompous," this suggests someone who uses complex language to appear more intelligent than they are.

* Pedantic: This describes someone who focuses on minor details and uses unnecessarily complex language, often making the conversation less enjoyable.

* Sesquipedalian: This is a humorous, somewhat archaic term for someone who uses long words, derived from the Latin word for "foot and a half," referencing the length of such words.

The best word to use will depend on the specific situation and the impression you want to create.