Adjective
exonic (not comparable)
Of or pertaining to an exon.
In tandem genomic duplication, due to the similarity between consensus donor and acceptor splice sites, which both closely resemble AGGT, the tandem genomic duplication of an exonic segment harboring an AGGT sequence generates two potential splice sites. Source: Internet
Intronization is the process by which mutations create novel introns from formerly exonic sequence. Source: Internet