Fungible \FUHN-juh-buhl\ , adjective;
1. Law: Freely exchangeable for or replaced by another of like nature or kind in satisfaction of an obligation
1. Something that is exchangeable or substitutable, usually used in the plural
The noun form of this word dates to 1765 and the adjective dates to 1818. It came to English as a legal term from Middle Latin fungibilis, which is derived from Latin fungi ("perform"). Fungi comes from the Proto-Indo-European base *bheug- ("to use, enjoy").
It appears as though this fungi has no connection with fungus.
Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Thursday, May 19
Etymologies come from the Oxford English Dictionary and/or Etymonline.com