An mRNA containing information from more than one gene.

Polycistronic mRNAs

Explanation:

Normally In Eukaryotic cells the messenger RNAs (mRNA) only contain the information to produce a protein, these mRNAs are known as monocistronic.

In Prokaryotes, the transcription system is usually polycistronic, this means that a mRNA have the information to encode two or more genes.

As an interesting example of the co-evolution of Eukaryotes, the mitochondrial genome has polycistronic genes.