Check on the IRS. See IRS Publication 501 starting on page 11 bottom Dependents
https://www.irs.gov/pub/irs-pdf/p501.pdf
And Turbo Tax, Who can I claim as a dependent?
https://ttlc.intuit.com/community/credits-and-deductions/help/who-can-i-claim-as-my-dependent/00/267...
