Definition of jiggers:
(n) :
(US) A double-ended vessel, generally of stainless steel or other metal, one end of which typically measures 1½ fluid ounces (approx. 44 ml), the other typically 1 fluid ounce (approx. 30 ml).
(n) :
(US) A measure of 1½ fluid ounces (approx. 44 ml) of liquor.
(n) :
(US, slang) A drink of whiskey.
(n) :
(mining) The sieve used in sorting or separating ore.
(n) :
(mining) One who jigs; a miner who sorts or cleans ore by the process of jigging.
(n) :
(pottery) A horizontal lathe used in producing flatware.