What does the word pellucid mean?

The simple meaning of the word pellucid is clear. But, it is also known that pellucid is formed from Latin per ("through") plus lucidus—a word meaning "lucid, clear" that ultimately derives from the verb lucēre, meaning "to shine." In English, Lucēre has many shining relatives. Among them are translucent (essentially, "clear enough to allow light to pass through"), elucidate ("to make clear, explain"), lucent ("luminous" or "clear"), and of course lucid itself (which can mean "shining," "mentally sound," or "easily understood").

Plus, another related word is Lucifer (a name for the devil that literally means "light-bearer"). Other relatives—such as lackluster ("lacking brightness"), illustrate (originally, "to make bright"), and lustrous ("shining" or "radiant")—trace from the related Latin verb lustrare ("to brighten"). Obviously, pellucid is just one of a family of brilliant terms.