Uparaja or Ouparath, also Ouparaja (Burmese: ဥပရာဇာ, IPA: [ṵpəjàzà]; Thai: อุปราช, rtgs: Upparat; Lao: ອຸປຮາດ; Oupahat), was a royal title reserved for the viceroy in the Buddhist dynasties in Burma, Cambodia, and Laos and Thailand, as well as some of their minor tributary kingdoms.
The Great Deputy King, in full Maha Uparaja Anaudrapa Ainshe Min, incorrectly interpreted as Crown Prince by Europeans, and addressed as His Royal Highness, was the single highest rank among the Min-nyi Min-tha, i.e. princes of the royal blood. It is shortened to Einshay Min (အိမ်ရှေ့မင်း, IPA: [èiɴʃḛ mɪ́ɴ]).
However, the position was not reserved for the highest birth rank (if there is one, Shwe Kodaw-gyi Awratha, i.e. eldest son of the sovereign, by his chief Queen), nor did it carry a plausible promise of succession, which was usually only settled in an ultimate power struggle.
Uparat (Thai: อุปราช; rtgs: Upparat) as pronounced in historical Siam, translates to viceroy.Front Palace (Thai: วังหน้า; rtgs: Wang Na), however, was the more usual designation, often referred to in English as Second King or Vice King.