Why is the ninth month called September?
early 14c., from Old French equite (13c.), from Latin aequitatem (nominative aequitas) "equality, conformity, symmetry, fairness," from aequus "even, just, equal" (see equal). As the name of a system of law, 1590s, from Roman naturalis aequitas, the general principles of justice which corrected or supplemented the legal codes.
In real estate, the financial value of someone's property over and above the amount the person owes on mortgages. For example, if you buy a house for $100,000, paying $20,000 down and borrowing $80,000, your equity in the house is $20,000. As you pay off the principal of the loan, your equity will rise.