From Longman Dictionary of Contemporary EnglishA-roadA-road /ˈeɪ rəʊd $ -roʊd/ noun [countable] a type of road in Britain that is smaller than a motorway, but larger than a B-road
Examples from the Corpus
A-road• That's likely to join up with a new A-road to East Anglia.• Show these cars a twisty, wet A-road, though, and the Limited transforms from man to He-man. 