knackered

Etymology 1

From the verb knacker.

adj

1. (UK, Ireland, Australia, New Zealand, slang) Tired or exhausted.
   I've got this job in a warehouse just now and it finishes quite early but I'm dead knackered at the end of the day so I don't know about going out and like studying every night. 2002, Robert Edenborough, Effective Interviewing: A Handbook of Skills and Techniques, pages 97–98
   2003, Hugh Dauncey, Geoff Hare (editors), The Tour de France, 1903-2003: A Century of Sporting Structures, Meanings and Values, Frank Cass Publishers, London, 2005, page 225, Then, it all just gets worse and worse, you don't sleep so much, so you don't recover as well from the day's racing, so you go into your reserves, you get more knackered, so you sleep less... It's simply a vicious circle.
   So my joy at hearing his voice quickly turns to a paroxysm of anxiety as he manages by exhausted gesture and sound to let us know how knackered he feels, how desperate to get horizontal, almost from the first moment he lands in the chair. 2009, Grace Maxwell, Falling & Laughing: The Restoration of Edwyn Collins, page 84

verb

1. simple past and past participle of knacker

Etymology 2

From "ready for the knacker's yard" or "fit to be knackered", meaning "worn-out livestock, fit to be slaughtered and rendered".

adj

1. (UK, Ireland, South Africa, colloquial) Broken, inoperative.
   In the end though he had to admit that the car was knackered... 2003, Simon Murphy, The Murders of Mutchrose Village, page 28
   We take an old knackered machine out to China and say, 'Copy that, brand new,' and they do. 2009, John Newton, Vance Miller - Kitchen Gangster?, page 82