General or controversial terms
Ahimsa
Non-violence in thought, word and deed.
A central concept of Jainism, and the first Yama of Hinduism.
Aryan Invasion Theory
The Aryan Invasion Theory is a hugely controversial idea that many current Hindus feel to be both discredited and inconvenient, even dangerous. It deals with the supposed ethical and cultural origins of Indian people and, at least to a degree, of Hinduism.
Atheism
A controversial subject within Hinduism, not so much in Jainism and Buddhism.
A popular view is that it is not possible to take the Vedas at all seriously, or to attain Sat-Chit-Ananda, without at least a modicum of faith on the existence of the Deva as literal supernatural beings.
Another, irreconcilable one is that the Devas are largely symbolic and/or inspirational and literal belief in their existence has never been needed for Hindu religious practice.
The general trend is clearly towards being at least unconfortable with (and often very critical of) Atheism, though.
Bhajan
A Hindu term for devotional songs, closely related to Bhakti practice.
Bhakti
An important and popular form of religious practice centered on devotion to some form of deity. Usually involves prayer, chanting and/or music. The name comes from the Hindu or Sanatana Dharma tradition, but Bhakti is definitely present and popular with other religions as well, albeit not always under this name.
Buddha Dharma - see Buddhism.
Buddhism
Buddhism is a Dharmic religion originated loosely around year 600 BC. It is usually considered Nastika Dharma by Hindus. A minority yet sometimes emphatic view insists that it is in some ways an extension of Hinduism. Syncretism with Hinduism is not unheard of, although often challenged. It is often understood that the Vajrayana schools of Tibetan Buddhism have been significantly influenced by Hinduism.
Cārvāka
Also known as Charvaka and as Lokāyata.
A historically Indian system of beliefs that is generally considered to be extinct and atheistic, materialistic and skeptical in nature.
While it has on occasion been considered part of Hinduism, that is definitely a minority opinion, and possibly a complete classification error.
Daoism - see Taoism
Dharma
Loosely translated as "doctrine", "religion", or "path", but also as "virtue", "duty" or "morality". The actual meaning is often dependent on context.
Dharma tends to value a line of transmission of religious knowledge. It is common and perhaps usual for the value of a Dharma to be understood as a function of the perceived wisdom both of the practicioner and of his or her religious teachers.
Guru
Religious teacher. A term typically used in Hinduism and of particularly strong meaning in Sikhism.
Henotheism
Belief that while God is ultimately one and supreme, he may well manifest in a variety of aspects that are themselves divine, yet never unconnected or truly distinct from the Supreme God. Typical of Hinduism. May in practice be nearly indistinguishable from Monotheism.
Hinduism
Usual name for Sanatana Dharma in the current times.
Jain Dharma - see Jainism.
Jainism
Jainism is a Dharmic religion originated loosely around year 600 BC. It is usually considered Nastika Dharma by Hindus. It is known to strongly emphasize the concept of Ahimsa (non-violence) that it shares with Hinduism.
Niyama
Duty or obligation, roughly equivalent in meaning to "virtuous behavior".
See also Yama.
In Hinduism there are five or ten (depending on the source) traditional Niyamas.
Panentheism
Religious doctrine that describes God as both transcending the material universe and being always strictly linked to it. Panentheism is compatible with a remarkable variety of Faiths, but is particularly noticeable in Sikhism. It can also be held as an autonomous or even custom belief, without necessarily being attached to an organized religion or Dharma.
Sanatana Dharma (also Sanatan Dharma)
  1. As generally understood, Sanatana Dharma (Eternal Dharma, loosely translated as Eternal Doctrine) is a traditional name for Hinduism. See also Vaidika Dharma (a name that references the Vedas) and Arya Dharma (which references the Arya people).
    Perceived advantages of that interpretation include its undeniable demographic success and lessened potential for unintentional confusion and misundestandings.
    Perceived disadvantages include a lack of expression of desire to reach out for doctrines, practices and teachings that are not generally understood as Hindu. In some contexts that may be undesirable. It has been noted that this is basically the flip side of the perceived advantages above.
  2. An alternate interpretation of the expression, often used in contexts where it is desired to express approval and/or admiration for the efforts of religious groups, teachers or authors, is that any valid and constructive religious action may be considered in harmony with the deepest goals of Hinduism and should therefore be praised as part of Sanatana Dharma. It amounts to a deliberate blurring of the boundaries between Hindu teachings and non-Hindu teachings, as a display of respect and/or appreciation.
    Perceived advantages of this interpretation are the expression of trust and good will, which are understood to encourage mutual respect and understanding, which are of course universally desired.
    Perceived disadvantages of this interpretation are the potential for confusion, often unintended and even well-meaning but nevertheless undesirable. Anedoctal evidence exists of at least one instance where it led to a misunderstanding, with a Catholic ending up believing that Catholicism is seen by Hindus as an universal religion while also being fundamentally distinct from Hinduism. That episode is generally understood as being a benign yet regrettable stance of undue extrapolation.
    It should also be noted that deciding to label people as Sanatana Dharmi (practicioners of Sanata Dharma) without their approval, agreement, consent or sometimes even without their knowledge is generally understood as an unwise, adharmic action since it so easily leads to ill feelings for no good reason. It has also been stated that it is, by definition, invasive.
  3. Another alternate interpretation says that some or all religions generally understood to have a Dharmic approach (most often Jainism, Buddhism, Sikhism, sometimes Taoism or even Confucionism; opinions may vary) are to be considered as part of Sanata Dharma as well. Historical links, well-documented or speculative, are often mentioned as part of the justification for this interpretation.
    Perceived advantages of this interpretation are mainly of a syncretic bent. It is favored by those who have a high regard for reaching out for other Dharmas.
    Perceived disadvantages include the potential for creating conflict due to perceived or real misunderstandings. It must be noted that efforts at communicating with other Dharmas are not without dangers of their own. Under some circunstances, attempting to present a common legacy or origin may easily be seen as disrespectful and/or invasive.
Sanatan Sikhi
A movement of a minority of Sikhs who view Sikhism as part of Sanatana Dharma as opposed as a separate Dharma of its own.
Sikhism
Sikhism is a 15th century religion that is both revealed, emphatically monotheistic and Dharmic. Sikhism's view of God is markedly panentheistic.
Taoism, also known as Daoism
A traditional religion of Chinese origin, arguably Dharmic in nature. Unlike most Dharmic faiths, Taoism has no clear historical relationship to Hindu beliefs and may not always be considered Dharmic.
Yama (Not to be confused with Lord Yama, the Deva of Death)
Behavior restriction, seen as necessary for ethical conduct. See also Niyama.
In Hinduism there are five or ten (depending on the source) traditional restrictions necessary for ethical conduct.
My great thanks to: