Etymology From quasi- + species. Noun English Wikipedia has an article on:quasispecies modelWikipedia quasispecies (plural quasispecies) (taxonomy) A group of organisms once (but no longer) thought to be a separate species (and sometimes given such a name) (genetics) A group of similar nucleic acid molecules; a group of organisms (especially viruses) having such similar genomes. Related terms infraspecificsubspecies See also cultivarstrainvariety