Go to 
A middle FICO Score is a borrower’s second highest FICO Score among what the three major credit reporting agencies (Experian®, Equifax®, and TransUnion®) report. This is the score mortgage lenders generally use when they qualify homebuyers for home loans. If there is more than one borrower on a loan, lenders typically use the score reported for the borrower with the lowest middle FICO Score.
Further reading
What Makes Up Your Credit Score?
See also FICO® Score
