“capable of being used in place of another; capable of being replaced,” 1818, a word in law originally, from Medieval Latin fungibilis, from Latin fungi “perform” (see function (n.)) via phrases such as fungi vice “to take the place.” Earlier as a noun (1765).
Fungibility
In economics, fungibility is the property of a good or a commodity whose individual units are essentially interchangeable, and each of its parts is indistinguishable from another part. For example, gold is fungible since a specified amount of pure gold is equivalent to that same amount of pure gold, whether in the form of coins, ingots, or in other states