1. Of, relating to, or dealing with existence.
2. Based on experience; empirical.
3. Of or as conceived by existentialism or existentialists: an existential moment of choice.
4. Linguistics Of or relating to a construction or part of a construction that indicates existence, as the words there is in the sentence There is a cat on the mat.
You really need to read the book 1984 - for starters because I assume this is your home work. Secondly, because 1984 was written by a man who extrapolated the progressive destruction of society in a modern time (ie - watch the news - Orwell was a few decades off, but correct in quite a few of his assumptions of a disintegrating society's structure.)
I'll throw you a bone though - you should examine the use of sex and procreation practices in 1984 versus the 'traditional' methods used in society today. How we are born plays a role in how we perceive our existence does it not?