Damnation is the concept of being separated from Heaven or divinity. It is a state of constant suffering or punishment, and the specific idea of damnation varies according to religions or beliefs. It is essentially the opposite of Heaven, though it is distinct from purgatory, which is a state of limbo in which the soul of a person may still be saved. In Christianity, souls experience damnation by being cast into hell; the only opportunity for salvation lies in turning to God before death. The term may also be used as a profanity.
The concept of damnation in Christianity involves a soul being turned to hell rather than Heaven. Hell is often portrayed as a place in which souls are doomed to spend eternity burning in fire, though the interpretation of this image may or may not be literal. It is a place reserved for humans who have rejected God in life by committing sins for which they have not atoned. Over the course of centuries, the severity of the sins which will cast a soul to hell have varied significantly, though mortal sins such as murder are generally considered to be sins that will damn a soul to hell.
Some Christians believe hell to be a physical place within the earth, while others feel it may exist in a separate dimension. Others believe it is a spiritual place that cannot be reached in the physical world; still others believe it to be a figurative place that does not actually exist but is instead a concept or spiritual state. The use of the term "damnation" implies the existence of an afterlife, so damnation is not a blanket term used by all people or faiths. Some religions and belief systems do not recognize an afterlife, so damnation is not possible.
The term "damnation" has evolved as well, and it has become a profanity that essentially means to damn to hell. It has lost some of its impact over the course of centuries, however, as it is often used as an interjection or mild cuss. The term itself is not used as often as its variants, such as goddamn, dammit, damn you, or simply damn, which is a shortened version of damned. The weight of the term was at one time quite significant, and it was considered a significant curse, but as centuries passed, the term lost its weight somewhat and is more likely to be considered a passing phrase.