pin money

noun2

1. •
   (historical) An allowance of money given by a man to his wife or to other dependents for their personal, discretionary use.

   • Damn you for a Son of a Bitch! Shall you wear such Things, and I want Pin-Money? — 1723
2. •
   (old-fashioned) A relatively small sum of cash kept in one's personal possession for routine expenses or incidental purchases; an amount of money which is not particularly significant.

   • "Money—yes; pin money: a couple of hundred thousand, perhaps. Not more." Washington's eyes blazed. "A couple of hundred thousand dollars! do you call that pin money?" — 1892