Noun
exonization (countable and uncountable, plural exonizations)
(genetics) Recruiting of a new exon from non-protein-coding, intronic DNA sequences.
Exonization is the creation of a new exon, as a result of mutations in intronic sequences. citation Polycistronic messages have multiple ORFs in one transcript and also have small regions of untranslated sequence between each ORF. Source: Internet