wack

1
[wak]Slang.
adjective
  1. very bad: All drugs are bad, but crack is wack.
  2. extreme; far-out.

Origin of wack

1
First recorded in 1935–40; perhaps back formation from wacky
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for wackest

wack

wacker (ˈwækə)

noun
  1. Liverpool and Midland English dialect friend; pal: used chiefly as a term of address

Word Origin for wack

perhaps from dialect wack or whack to share out, hence one who shares, a friend
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for wackest

wack

n.

"crazy person," 1938, back-formation from wacky. Adjective in slang sense of "worthless, stupid," is attested from late 1990s.

Online Etymology Dictionary, © 2010 Douglas Harper