Final answer:
In France, Tannat is known by its original name. In Spain and Uruguay, it goes by the synonym Harriague, named after Basque settler Pascual Harriague who introduced Tannat to Uruguay.
Step-by-step explanation:
The grape variety Tannat is known by different names in various countries due to local dialects and naming conventions. In France, Tannat retains its name and is primarily grown in the Madiran region. In Spain, however, Tannat is known by the synonym Harriague, this name is not very common as the grape itself is not widely cultivated in Spain. Meanwhile, in Uruguay, Tannat is also referred to as Harriague. The arrival of the Tannat grape in Uruguay is largely credited to Basque settlers, and the synonym Harriague is derived from one of these settlers, Pascual Harriague, who played a significant role in the introduction of this grape variety to the country.