The Inca referred to their empire as Tawantinsuyu, “the four suyu”. In Quechua, tawa is four and -ntin is a suffix naming a group, so that a tawantin is a quartet, a group of four things taken together, in this case the four suyu (“regions” or “provinces”) whose corners met at the capital. The four suyu were: Chinchaysuyu (north), Antisuyu (east; the Amazon jungle), Qullasuyu (south) and Kuntisuyu (west). The name Tawantinsuyu was, therefore, a descriptive term indicating a union of provinces. The Spanish transliterated the name as Tahuatinsuyo or Tahuatinsuyu.
The term Inka means “ruler” or “lord” in Quechua and was used to refer to the ruling class or the ruling family. The Incas were a very small percentage of the total population of the empire, probably numbering only 15,000 to 40,000, but ruling a population of around 10 million people. The Spanish adopted the term (transliterated as Inca in Spanish) as an ethnic term referring to all subjects of the empire rather than simply the ruling class. As such, the name Imperio inca (“Inca Empire”) referred to the nation that they encountered and subsequently conquered.