From Merriam-Webster:
1a. Marked by transparency
b. Clear and simple in style
2. Absolutely serene and untroubled
Clear, Transparent, Translucent,
Limpid mean capable of being seen through.
Clear implies absence of cloudiness, haziness, or muddiness. clear water
Transparent implies being so clear that objects can be seen distinctly. a transparent sheet of film
Translucent implies the passage of light but not a clear view of what lies beyond. translucent frosted glass
Limpid suggests the soft clearness of pure water. her eyes were limpid pools of blue
Since the early 1600s, "limpid" has been used in English to describe things that have the soft clearness of pure water. The aquatic connection is not incidental; language scholars believe that "limpid" probably traces to "lympha," a Latin word meaning "water." That same Latin root is also the source of the word lymph, the English name for the pale liquid that helps maintain the body's fluid balance and that removes bacteria from tissues.
From Dictionary.com:
First recorded in 1605–15, limpid is from the Latin word limpidus clear.
From Vocabulary.com:
1. clear and bright
2. transmitting light; able to be seen through with clarity
3. (of language) transparently clear; easily understandable