1. wakeful, easy to be awaked ...1790 Eng. dial.
2. larger than ordinary ...Bk1912 Eng. dial.
3. excellent, wonderful ...1940s Aust. sl.
1. anything abnormally large or notable of its kind; a big lie; a heavy blow, a thump ...1770
2. a driver of animals; a drover; an ox or mule driver ...1827 Amer. dial.
3. a police truncheon ...1916 UK criminals' sl.
4. something excellent ...Bk1942 Amer. sl.
5. (also WACKER) an affectionate or teasing term of address ...1949 sl.
6. (also WACKER) a masturbator ...1965 sl.
7. (also WACKER) a fool ...1965 Aust. sl.
8. a person who is seriously mentally unstable ...1965 Aust. sl.
9. a gadget, a thing ...20C US sl.
10. the penis ...20C US sl.
11. a small glass of brandy ...1993 Irish sl.
to tremble, to shake, to quake ...Bk1828 Eng. dial.
for n. 2. - from whack (vb. to beat or strike vigorously ) + -er
FIRST DOCUMENTED USE
1770 - see EXAMPLE below
"...On this Ulysses turn'd about,
And fell to pummelling the rout:
To Cromeus, an East-India packer,
He lent a knock, and such a whacker,
It brought him down; then bold Alester
He soon sent off to beg a plaister..."
From: A Burlesque Translation of Homer, Volume 1
- Thomas Bridges
A Burlesque Translation of Homer, Volume 1By Thomas Bridges