Typically Hindu concepts
Advaita
One of the (traditionally six) Astika schools of Hindu thought.
Agnitra
The protector of the fire; the keeper of the fire; he that holds the fire; Vedic Shrautin; yajna-dharma
The agnitra is a common theme in the Vedas. It is a compound term that literally means the keeper of the fire, where the fire is understood to be that present in the yajna.
Illustration (Warning: big picture, established to be online as of 2014-04-29).
Arya Dharma
A traditional name for Hinduism. Often seen with a degree of caution because it may bring unfortunate associations with the "Aryan Race" ideal as espoused by Nazi philosophy.
Astika
In simple terms, Astika Dharma is Hinduism proper, a Dharma that attempts to follow the teachings of the Vedas. Those include Samkhya, Mimamsa and Vedanta schools of thought.
Avatar
A manifestation or aspect of a Deva as another Deva or (perhaps) as an idealized human or even animal. A popular concept in Hinduism.
Deva, plural "Devas", feminine "Devi"
A concept somewhat similar to that of deity. Often referenced in the Vedas and other sacred texts of Hinduism and other Dharmic religions.
Dvaita
One of the (traditionally six) Astika schools of Hindu thought.
Mimamsa
One of the (traditionally six) Astika schools of Hindu thought.
Nastika
In simple terms, Nastika Dharma is a religious doctrine that has inherited concepts and cultural influence from Hinduism and may (or may not) be largely compatible and in harmony with Hinduism, yet claims no duty to follow the teachings of the Vedas.
It is generally agreed that Charvaka, Jainism and Buddhism are Nastika schools - at least according to Hinduism. Some or all of those movements might prefer to be regarded as religions of their own.
Samkhya
One of the (traditionally six) Astika schools of Hindu thought.
Sat
Truth; being truthful, fair, and righteous. Emphasized in Sikhism.
Sat-Chit-Ananda
Also known as Satcitananda and other variant spellings. While Sat (loosely translatable as "truth", "absolute" or "unchangeable"), Chit ("true/pure consciousness") and Ananda ("beauty", "happiness" or "pleasure") are all individual words, this composite is a traditional name for the superlative experience of Brahman, and a very important concept of Hinduism.
Vaidika Dharma
Literally the Dharma from (or of) the Vedas. An alternative name for Hinduism.
Vedanta
One of the (traditionally six) Astika schools of Hindu thought.
Vedas
The main (or at least the most ancient) scriptures of Hinduism. Not necessarily the most read or the most influential, though; notably, the well-regarded Bhagavad Gita and its parent text, the Mahabharata, are not Vedas, at least in the traditional sense.