The two words are synonyms, and from the dictionary checking I've
done, they seem virtually interchangeable.  But ... what nuance of
difference between them would help the precise writer know when to use
one and when to use the other?

mikeginnyc-ga,

According to the Oxford English Dictionary, the key difference between
the terms is that limpid almost always applied to liquids, while
pellucid can find use more generally to refer to clarity of numerous
sorts, including clarity of thought, clarity of tone, etc.

A pool of water may be aptly described as pellucid, though one is
probably more likely to use the term limpid.

However, a well-formed logical argument would likely be described as
pellucid, to refer to the clarity of presentation, rather than limpid.

Neither term is used with great frequency is this regard, though:


://www.google.com/search?num=100&hl=en&lr=&rls=GGLD%2CGGLD%3A2003-43%2CGGLD%3Aen&q=%22pellucid+argument%22
"pellucid argument"  -- 6 hits



://www.google.com/search?num=100&hl=en&lr=&rls=GGLD%2CGGLD%3A2003-43%2CGGLD%3Aen&q=%22limpid+argument%22
"limpid argument" -- 3 hits


Let me know if there's anything else I can do for you on this.


pafalafa-ga

---

Clarification of Answer by pafalafa-ga on 14 Jul 2006 11:36 PDT

mikeginnyc-ga,

Thanks for the kind feedback.  Sorry about the notification.  There is
definitely some sort of glitch in the system, which is a shame, as it
makes communications rather clumsy.  Hope it clears up soon.

Thanks again,

paf

I == never == received an email notification from Google that this
question had been answered ... and I was disappointed/thought it odd
that no one did.  I gave up on it ... but when I came back to ask a
NEW question, I saw that it had been.  My apologies to the researcher
who answered it long ago, but shame on Google for not TELLING me it
had been answered.

While they are essentially the same in definition, limpid has the
quality of being calm or serene. Pellucid is not given this added
dimension.

Having said that, I believe the big difference is the "ear" of the
word. Limpid sounds soft, cuddly, squishy, pleasant, almost hypnotic.
Limp... id.

                           *sigh* 

Pellucid starts hard-- P-- and begins to sound like "pollution." While
it does have "loose" in it, you can't really tell 'cuz you don't hear
it. You hear "lucid" and think of sanity hearings.

So on the one hand you've got a squishy word that's gentle and calm;
on the other is one that starts off spitting at you and ends up in
court explaining why exactly you had to nail those seven lying
muskrats to the fencepost to stop their derisive snickering at 3AM and
reclaim your vital humours they were siphoning off into a blue '47
Plymouth Special Deluxe.

*** this is priceless! ***

Yes, quite! :)

You might try searching with    define:limpid     define:pellucid

to see definitions of each word.