A and B are two persons. When A is a dependent of B, what of A is B?
marked as duplicate by RegDwighт♦ Aug 6 '12 at 8:53
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Depending on the circumstance, if A is the dependant of B, then B may be the guardian of A. As tchris noted, this would apply for a parent-child relationship, but it does not fit when referring to spouses.
Perhaps the term provider or the phrase principal provider conveys the relationship.
SUPPLEMENT: I think JLG is right that this is a duplicate (and others have suggested what I propose).