From the Sanskrit अवतर or अवतार avatāraḥ, meaning "descent" (of a deity from heaven), avatar: ava, down + tarati, "he crosses." An incarnation of the cosmic, universal Christ (Vishnu, Chokmah).
Samael Aun Weor used the term "avatar" to mean "messenger."
"The reincarnated Christ expresses himself through every authentic avatar. " - Samael Aun Weor, The Gnostic Bible: The Pistis Sophia Unveiled
"...the Omni-merciful, the infinitude that sustains all, the very, very sacred Absolute Sun, periodically sends Avatars, Saviors, to this valley of tears. These sacred individuals, these messengers, these Saviors, are living incarnations of the Omni-merciful. Nevertheless, this lunar race, this perverse race of Adam, mortally hates such helpers. [...] The blessed Krishna, the blessed Buddha, the blessed Lama, the blessed Mohammed, the loving, essential Ashiata Shiemash, Moses, Quetzalcoatl (and many others) were all Avatars. The doctrine of all Avatars has its roots in the three basic factors of the revolution of the consciousness: to be born, to die, and to sacrifice the self for humanity." - Samael Aun Weor, The Doomed Aryan Race
"Avataras appear for special reasons in special circumstances. Whenever there is much unrighteousness, whenever confusion and disorder set in on account of unrighteousness and baffle the well-ordered progress of people, whenever the balance of human society is upset by selfish, ruthless and cruel beings, whenever irreligion and Adharma prevail, whenever the foundations of social organisations are undermined, Avataras appear to establish Dharma and to restore peace. Avatara is a descent of God for the ascent of man. A ray from the Hiranyagarbha descends on earth with mighty powers to keep up the harmony of the universe. The work done by the Avataras and their teachings produce a benign spiritual influence on human beings and help them in their upward divine unfoldment and Self-realisation. The Avatara comes to reveal the divine nature in man and makes him rise above the petty materialistic life of passion and egoism." - Swami Sivananda, Lord Krishna, His Lilas and Teachings