Rajas
It refers to the law of nature that maintains life. It is one of the three gunas characterized by action, energy, passion and stimulation that leads to the life of sensual enjoyment, pleasure and pain, efforts and restlessness.

Rakshasa
It is a synonym for demons or demonic beings whose minds are unable to distinguish between right and wrong and is diverted towards conflicts and anger.
Literally meaning the blood, rakta is one of the seven dhatus supported by rasa and is responsible for the nourishment of the permanent dhatus, providing physical strength and color to the body. This circulating blood vessel is considered as the basis of life.

Ram
In Hindu mythology ram is the seventh incarnation of Vishnu and the warrior hero of the holy Hindu epic, the Ramayana. He is also regarded as the embodiment of righteousness.

Ranjaka
Located in the stomach, liver and spleen it is one of the five pitta subdoshas, liver and spleen. Its function is to give color to the lymph chyle when it is transformed into blood as it passes through the liver and spleen.

Rasa
It is derived from the digested food and is circulated the entire body by channels. The main function of this first of the seven dhatus is to provide nutrition to all cells of the body and the plasma dhatu.

Rasayana
Literally means rejuvenation i.e. the therapy that rejuvenates or regenerates body- mind, prevents decay and postpones aging.

Rechaka
It refers tot he exhalation aspect of pranayama, the out breath.

Rasa-vaha srotas
Channels carrying plasma or lymph.

Rasi
Quantity, a measure for quantity, a heap, a pile, mass.

Ratricarya
Routine to be followed in night or evening, night regime.

Ritucarya
Seasonal regimes, routine to be followed in various seasons.

Ruksa
Dry, arid, not greasy, emaciated, thin.

Rupa
Sign, symptoms, mark (of diseases).