1. A minor road or route that is less traveled than main highways; typically smaller, rural roads that serve as alternatives to major thoroughfares
We took a back road to avoid traffic on the highway.
Pegamos uma estrada secundária para evitar o trânsito na rodovia.
2. A route that is indirect or not the most obvious choice between two locations
He knew all the back roads through the countryside.
Ele conhecia todas as estradas secundárias pela zona rural.