referendum (n.) Look up referendum at Dictionary.com
1847, "a submitting of a question to the voters as a whole" (originally chiefly in reference to Switzerland), from French or German, from Latin referendum "that which must be referred," literally "thing brought back," neuter gerundive of referre "to bring or take back" (see refer). As a gerundive, it has no plural in Latin; referendums is preferred in English.