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bitchin’

American  
[bich-in] / ˈbɪtʃ ɪn /
Also bitchen

adjective

Slang.
  1. great; wonderful.

    It was a bitchin' concert.


bitchin' British  
/ ˈbɪtʃɪŋ, ˈbɪtʃɪn /

adjective

  1. wonderful or excellent

"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

adverb

  1. extremely

    bitchin' good

"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

Etymology

Origin of bitchin’

First recorded in 1955–60; bitch + -in’, -en, informal or dialectal variant of -ing 2