yellow boy

noun3

1. •
   (slang) Iron(III) hydroxide, a yellow-orange solid found in acidic water from mining projects.
2. •
   (US, slang) Synonym of goldback (“kind of gold certificate”).
3. •
   (slang, no longer used) A gold coin; a guinea or sovereign.

   • “Damn them, (cried the commodore) I wish both their necks were broke, thof the two cost me forty good yellow-boys.” “Forty guineas! (exclaimed the stranger […]).” — 1751

noun1

1. •
   (informal) A Winchester Model 1866 lever action rifle.