Oblivion /əˈblivēən/ noun 

Definition: Oblivion refers to any of the following: 

1. The state of being entirely forgotten, not used or thought about anymore.
2. The state of being completely unaware or unconscious, not knowing what is happening around you at any time.
3. The condition or fact of not remembering anything.
4. Oblivion can also mean the state of being entirely destroyed.

Etymology: “Oblivion” was derived from Anglo-French and Middle English from Latin oblīvīscī, meaning to put out of mind or forget. Derived from Middle English oblivioun, borrowed from oblivion (Anglo-French). The Latin oblīvīscī stems from the prefix ob- meaning “facing, toward” and combined with līvīscī, which is an inchoative derivation of a stem līv-, of unknown origin and meaning.

Its literary synonym is lethe, originally referring to the mythical River Lethe. This river, according to Greek mythology, flowed via the Underworld and often induced forgetfulness (oblivion) among individuals who drank the river’s water.

In a Sentence

All the promises that aspiring politicians make during campaigns have a natural habit of fading into oblivion.

The military aircraft commandeered remotely bombed the little terrorist town into oblivion.

Mike has an unhealthy habit of drinking to oblivion when dealing with depression.

Synonyms 

Forgetfulness, Unconsciousness

Antonyms 

Consciousness, Awareness