genomic_island
A genomic island is an integrated mobile genetic element, characterized by size (over 10 Kb). It that has features that suggest a foreign origin. These can include nucleotide distribution (oligonucleotides signature, CG content etc.) that differs from the bulk of the chromosome and/or genes suggesting DNA mobility.
Genomic islands are transmissible elements characterized by large size (>10kb).
SO:0000772
genomic island
http://en.wikipedia.org/wiki/Genomic_island
sequence
integrated_mobile_genetic_element