Identity (noun)

1. The fact of being who or what a person or thing is.
2. The qualities, beliefs, etc. that make a particular person or thing different from others.
3. The condition of being the same as something else.
4. The state of being oneself and not another.
5. The set of characteristics by which an individual is recognized or known.

Origin:

Late middle english: from old french identite or medieval latin identitas, from latin identidem "in the same way".

Examples:

1. He had problems with his identity.
2. She has a strong sense of her own identity.
3. The company is trying to establish its identity in the market.
4. The detectives are trying to establish the identity of the suspect.
5. He questioned his own identity.