Which definition best describes "limpid"?

The term "limpid" is best defined as clear and transparent. This definition captures the essence of the word's usage, which often relates to clarity in both a physical sense, such as clear water, and in a figurative context, indicating a clear and easy-to-understand expression or thought. The idea of being transparent or easily understandable aligns with how "limpid" is typically presented in literature and conversation.

The other definitions do not align with the meaning of the word. For instance, the opposite characteristics of being opaque and difficult to understand are completely contrary to the concept of clarity inherent in "limpid." Similarly, being colored and vibrant or dark and mysterious does not relate to the idea of transparency or clarity that "limpid" embodies. Understanding "limpid" as a term denoting clarity helps in grasping its applications across various contexts.