Definition of "fungible"

Take away this fungible instrument from the service of our necessities and how shall we exercise our Charity, which is a branch of Religion and Justice, as well as of Humanity?

1649, Antony Ascham, Of the confusions and revolutions of governments, page 30

Gold is fungible. Silver is fungible; that is, these metals are both so homogeneous that, if I get a pound of pure gold, for example, it is indifferent to me whether it be this pound or that pound, one is as good as another

1876, Samuel Dana Horton, Silver and Gold and Their Relation to the Problem of Resumption, page 116

At the core of Kasarda’s conception of the aerotropolis lies the notion that space – unlike time – is fungible.

2011, Will Self, “The frowniest spot on Earth”, in London Review of Books, XXXIII.9

However, unless you are unique among technical organizations and have fungible staff members who can easily replace each other, you'll need to augment the standardized description with your needs for this particular position.

2013, Johanna Rothman, Hiring the Best Knowledge Workers, Techies & Nerds

The archetypical fungible is money: if I drop a £1 coin in the street it is a matter of indifference to me whether I pick up that coin or another £1 coin lying next to it.

2005, Alison Clarke, Paul Kohler, Property Law, Cambridge University Press, page 52