cold cash

Also, hard cash. Actual currency (bills and coins); money immediately available, paid at the time of a purchase. For example, Will you lower the price if I pay in cold cash instead of using a credit card? or We have only a limited amount of hard cash--the rest is in accounts receivable. [First half of 1900s]

The noun has one meaning:

Meaning #1: money in the form of bills or coins
  Synonyms: cash, hard currency