Slang A person regarded as eccentric or irrational: "a catchy pop portrait of a wacko who talks to himself in French” ( Phoebe Hoban). (noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "wacko" in a sentence
"Looked at sufficiently askew (some might prefer the term wacko), everything is new under the sun."
"Get real this wacko is here to stay, afterall he is a Republican and that in itself makes him royalty ... just ask him."
"This dumb wacko is heading down the road to terrible change."