Multicistronic message is an archaic term for Polycistronic. Monocistronic, bicistronic and tricistronic are also used to describe mRNA with single, double and triple coding areas (exons).

Note that the base word cistron is no longer used in genetics, and has been replaced by intron

Intron

An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...

 and exon

Exon

An exon is a nucleic acid sequence that is represented in the mature form of an RNA molecule either after portions of a precursor RNA have been removed by cis-splicing or when two or more precursor RNA molecules have been ligated by trans-splicing. The mature RNA molecule can be a messenger RNA...

 in eukaryotic mRNA. However, the mRNA found in bacteria is mainly polycistronic. This means that a single bacterial mRNA strand can be translated into several different proteins. This will occur if spacers separate the different proteins, and each spacer has to have a Shine-Dalgarno sequence located upstream of the start codon.