What does rdx stand for acura?

In the Acura, RDX typically indicates that it is a resized MDX model. In most cases, the resultant RDX models are smaller MDX models with some additional features that are included only in the luxury editions of the Acura. Essentially, the RDX can be thought of as the SUV version of the MDX, as the MDX has continued to grow not just in form factor, but also in price. As a result, the Acura works as somewhat of a budget or value offering in the SUV category. It could also be a generic serial code with no real inherent meaning. That being said, the consistent features acroSSRDX models lead one to believe that it is a smaller brother of sorts to the MDX.