From Hindupedia, the Hindu Encyclopedia
By Swami Harshananda
Nāstika literally means an ‘atheist’.
A nāstika is the one who says ‘It does not exist!’ It can be split as "na" which means not and "asti" which means exist. He does not believe in the existence of God, the soul, after-life, heaven and hell. In fact he does not believe in all that which cannot be experienced by the five sense-organs.
- The Concise Encyclopedia of Hinduism, Swami Harshananda, Ram Krishna Math, Bangalore