Commonly used in Spain, Portugal and some South American countries as a name element or synonym for many different white grape varieties. The confusion is exacerbated by different spellings ("o" and "u"). Particularly in the case of the varieties cultivated in Portugal and Spain, it is often unclear which exactly is meant. Also the Portuguese DOC or Spanish DO regulations as well as vine variety catalogues are of no help if only "Torrontés" is mentioned there.
Source: Wine Grapes / J. Robinson, J. Harding, J. Vouillamoz / Penguin Books Ltd. 2012