n.
An eccentric person, especially one with bizarre ideas.
adj.
Foolish; harebrained: a crackpot notion.
[CRACK(ED) + POT1, skull (obsolete).]
The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.