Definition - What does Solid mean?
Solid is a term used to describe a wine that shows no obvious flaws and is balanced. It is a vague term and is neither seen as a compliment or otherwise, but simply states the wine is good and well-made. In a negative connotation, "solid" might mean that the wine is nothing special.
WineFrog explains Solid
There is some wine terminology that can be a little vague to understand unless the context is given. Some tasting notes may be difficult to interpret as positive or negative.
If a wine is said to be "solid", it is best if all the tasting notes are understood. For instance, if a wine is said to be "full of layered, early summer fruits like currant and raspberry, with bright, subtle acidity and soft, even tannin on the finish. A solid wine." Then "solid" in this aspect is a positive note, and says the wine is in balance and enjoyable.
If a wine is tasted and simply described as only "solid", then the wine is ready-to-drink, with no potential for aging and a simple, good wine, nothing exciting.