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In the religion and mythology of Peru, Ecuador, and Bolivia, apus are the spirits of the mountains - and sometimes solitary rocks and caves, that protect the local people in the highlands. The term dates back to the Inca Empire.
Meanings of Apu
The word "Apu" has several possible meanings, depending on context.
Apu (A-pu) means “Lord” in Qechua. The Inka religion uses the term Apu to refer to a mountain that has a spirit that is alive. Body and energy bubble of the mountain together form his wasi (Qechua for "home" or "temple"). 
Besides mountains there are other living beings that are considered as Apus - the so-called Tekse Apus. In the Andean tradition Pachamama (Cosmic Mother), Wiraqocha (God or Cosmic Father), Father Sun (Taita Inti), Father Wind (Taita Waira), Mother Water (Mama Unu), Mother Moon (Mama Killa) and Mother Stars (Mama Ch'aska) can be seen all over the world, that is why they are called Tekse Apus, which means Global Apus. Jesus Christ and Mother Mary for the same reason are also called Tekse Apus.
In fictional literature
According to one science-fiction novel, the natives know of extraterrestrials that claim to come from the planet Apu. Apparently they wish to keep this a secret, but the Apunians wish humanity to know all about them what this implies. An extract from this book, written by Vlado Kapetanovic;
"The stranger was silent for a moment, and then smiled at me and said: “We come from a planet we call APU, located outside the Milky Way Galaxy. We are protectors of the cells and the life. For this we are traveling through space to aid by different modes the planetary beings, but not to impress with the result that you believe in our existence and ‘extraordinary powers’” 
Other Apus in Bolivia and Peru are: Akamari, Antikuna, Chachani, Kimsa Chata, Illampu, Lady of Illimani, Machu Picchu, Pitusiray, Phutuq K'usi, Qullqipunku, Sinaqara, Tunupa, Willka Wiqi (Wakay Willka), Wamanrasu, Wayna Pikchu and Yanantin.
- Stevens, Wendelle; (2012-12-30). UFO CONTACT FROM PLANET APU Kindle Edition.