Green’s Dictionary of Slang

1. (Aus.) to castrate.

1984

Partridge DSUE (8th edn) 651/2: since ca. 1860.

2. to tire, to exhaust.

1908		Sheffield Eve. Teleg. 1 Dec. 5/6: ’They said,’ replied witness, ‘they had “knackered” Marks and they would knacker me.’ (Laughter.) I said I would take good deal of knackering. (Laughter.).
1988		R. Doyle Commitments 32: At first he jumped around but it was too knackering.
2001		N. Barlay Hooky Gear 60: The walin knacker me an walkin through the rain knacker me double.

3. to kill, to ruin.

1982		P. Redmond Tucker and Co 47: Don’t knacker it. Must have taken Roly ages to make that.
2000		Indep. Rev. 4 Feb. 15: Karma inevitably knackers his guitar 30 seconds later.