Word

Ketu

Sanskrit

केतु

IAST

Ketú

In General

Ketu is a chaya graham, a shadow planet. Ketu and another such planet known as Rahu were included in the nine planet of Indian astrology. Astronomically, Rahu and Ketu denote the points of intersection of the paths of the Sun and the Moon as they move on the celestial sphere. The eclipses happens when the Sun and the Moon are at one of these points; this give rise to the feeling that the Sun and the Moon are being swallowed by the snakes known as Rahu and Ketu during elclips.

Veda

Ketu is the power of intuition. The word occur 66 times in R.V. Ketu is opposite of aketu, which means no intuitive power

Purana

Ketu and Rahu are feared in Purana. Ketu is generally known as the planet of illusion, detachment, spirituality, asceticism, but tamasik in nature. It is not as malefic as Rahu. Ketu and Rahu are half-bodied representing spiritual and material possessions. Ketu is with only lower half body of a snake and Rahu with only the upper half. So, both of them are with incomplete body. It is also said that whatever Rahu gives, Ketu takes away. Rahu always dominate because of its materialistic nature, Ketu is submissive and susceptible.

Reference

R.V. 1.6.3