During the course of centuries the word Dharma has been used, in many contexts, and thus came to mean different things to different people.
Monier-Williams, gives its primary definition as:
‘That which is established or firm, steadfast decree, statute, ordinance, law; usage, practice, customary observance or prescribed conduct, duty; right, justice (often as a synonym of punishment); virtue, morality. religion, religious merit, good works.’ Out of these ‘that which is established or firm’; appears to be the best definition.
To this the Vedas add another important aspect: Dharma as duty.
‘Dharma’ derives from the verbal root dhr, which simply means ‘manner of being’. Conformity ‘to a Divine or Creative Principle’ at work in an individual and in nature. It represents the individual’s internal ‘law’, to which an obedience must be given if that individual life is to live in accordance with a Divine Wil - the sole or primary ‘purpose’ of life.
Rene Guenon, father of the 20th century ‘school’ of Perennial Philosophy, defines it as such: it (Dharma) is, so to speak, the essential nature of a being, comprising the sum of its particular qualities or characteristics, and determining, by virtue of the tendencies or dispositions it implies. The same idea may be applied, not only to a single being, but also to an organized collectivity, to a species, to all the beings included in a cosmic cycle or state of existence, or even to the whole order of the Universe; it then, at one level or another, signifies conformity with the essential nature of beings... (from Guenon’s ‘Introduction to the Study of Hindu Doctrines’).
In Hinduism, Dharma also is a synonym for the God of death Yama. In Buddhism, Dharma refers to the body of teaching of the Buddha. In the Vedas, Dharma meant Rta. Rta literally means the ‘course of things.’ At first, the early Hindus (or followers of the ‘Sanatana Dharma’) were notably confused as to the inscrutable order of nature, henceforth sprang Rta, whose all-purpose role it was to signify this order, the path that was always followed. Through all the metamorphoses and permutations of nature, of life in general, there was one unchangeable fact: Rta.
This idea firmly took root in the Indian ethos, Rta as the right path the path of the universe conjoint with the path of the society and the individual: Thus, we see the logical progression of an early ‘course of things’ into an all-encompassing moral order Vedic concept of Rta.
The Upanisads saw Dharma as the universal principle of law, order, harmony, all in all truth that sprang first from Brahman. It acts as the regulatory moral principle of the universe.
IN YOGA
In Yoga, the word Dharma is used in the context of duty; duty to oneself, to the family, to society and to God. The yoga student is enjoined to become skilful and conscious in his duties and that the world order ‘rta’ would then uphold him in all his activities.