ref·er·en·dum 
(rĕf′ə-rĕndəm)
(rĕf′ə-rĕndəm)n. pl. ref·er·en·dums or ref·er·en·da (-də)
1.
a. The submission of a proposed public measure or actual statute to a direct popular vote.
b. Such a vote.
2. A note from a diplomat to the diplomat's government requesting instructions.
[Latin, neuter gerundive of referre, to refer; see REFER.]