There are two different distinctions of dependents: qualifying child and qualifying relative. A dependent must be one of the two classifications.
Qualifying relative must meet all five conditions of relationship, gross income, support, citizenship or residency, and joint return test.
These dependents are required to be related in one of the following ways but don't have to live with you: children, grandchildren or great-grandchildren who don't meet the requirements for a qualifying child exemption, brother/sister and step-siblings; niece/nephew; in-laws; parents and step-parents; grandparents and great-grandparents; aunts and uncles related through blood only.
If a non-listed relative or unrelated person lives with you, and has created a domicile in your household for the entire tax year, (temporary absences aside), they may be able to meet the relationship test.
A dependent can't have a gross income greater than exemption amount to be claimed as a qualifying relative, regardless of the amount of support you have provided.
You have to provide the qualifying relative with over half of their total yearly support.
The relative must be a U.S. citizen or national, although a resident of the U.S., Canada, or Mexico is also eligible.
In order to claim the qualifying relative dependency exemption, the dependent can't file a joint return with their spouse (if married).