What is Agency Of Necessity?

Legal Definition
A term sometimes applied to the kind of implied agency which enables a wife to procure what is reasonably necessary for her maintenance and support on her husband's credit and at his expense, when lie fails to make proper provision for her necessities. Bostwick v. Brower, 22 Misc. Rep. 709, 49 N. Y. Supp. 1046.
-- Black's Law Dictionary