http://www.fafsa.ed.gov/help/ffdef07.htm
Who is considered a parent?
If your parents are married, provide information about both parents.
If your parent is widowed or single, provide information about that parent.
If your parents have divorced or separated, provide information about the parent that you lived with most during the last 12 months. If you did not live with one parent more than the other, provide information about the parent who provided most of your financial support during the last 12 months.
If your parent has remarried after being widowed or divorced, provide information about both your parent and your stepparent.
If you have a legal guardian, you cannot use your legal guardian’s information on your application. A legal guardian is not considered a parent in the financial aid process.
If you have foster parents, you cannot use your foster parents’ information on your application. A foster parent is not considered a parent in the financial aid process.
If you were adopted, follow the instructions above for parents, based on your adoptive parents’ current marital status.
Note: The following people are not considered parents on this form unless they have legally adopted you: grandparents, foster parents, legal guardians, older brothers or sisters, and uncles or aunts.