Oncidium is a genus of about 370 species of orchid in the family Orchidaceae. It is distributed across tropical and subtropical America from Mexico, Central America and the West Indies to northern Argentina, with one species (O. ensatum) extending into Florida. Common names for plants in this genus include dancing-lady orchid.

A molecular phylogenetic study published in 2009 labeled the Oncidium alliance "grossly polyphyletic." In the same year, the American Orchid Society labeled the genus a "dumping ground". A consensus announced in April 2013 resulted in major taxonomic changes to Oncidium, Gomesa, Odontoglossum, Miltonia, and others. Much of this debate and subsequent housekeeping was initiated by significant research for the scientific publication Genera Orchidacearum Volume 5. One significant change is the move of most Brazilian Oncidium with a fused lateral sepal to the genus Gomesa.

...