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1. larger than ordinary ...B1900 Eng. dial.
2. wakeful, easy to be awaked ...B1900 Eng. dial.
3. excellent, wonderful ...1940s Aust. sl.
1. anything abnormally large of its kind; a big lie; a heavy blow ...1823
2. a driver of animals; a drover; an ox or mule driver ...1827 Amer. dial.
3. a gadget, a thing ...20C US sl.
4. the penis ...20C US sl.
5. something excellent ...Bk1942 Amer. sl.
6. a fool ...1960s Aust. sl.
7. a masturbator ...1980s US sl.
to tremble, to shake, to quake ...B1900 Eng. dial.
from whack (vb.) + -er
From: Tom Brown's School Days
By An Old Boy (Thomas Hughes), 1857
Chapter IV, The Bird Fanciers, A Debate