Cohabitating/living together?

What are the legal definitions of living together and or cohabitating?
Living together is not a legal residence. Cohabitation, on the other hand, means that you are sharing a residence AND co-mingling the expenses.
There is no legal definition required for cohabitation....I suppose they could be referred to as "roommates." Each state have they're own law governing cohabitation. You need to refer to your state's guidelines.