From Longman Dictionary of Contemporary Englishon solid groundon solid groundconfident because you are dealing with a subject you are sure about, or because you are in a safe situation To make sure that he was on solid ground, he confirmed his findings with others. → solid
Examples from the Corpus
on solid ground• Our main objective is to get the city's finances onto solid ground.• Similarly, when Dole asserts that Clinton reduced the office of drug czar by 83 percent, he is on solid ground.• I sat on solid ground, my back against a tree.• We are on solid ground when we say that we will oppose this Bill. 