“Drip” is not an imitative word, according to the OED. It does not mean any sound except as a slang or naval term for complaining. Yet we all understand Tolkien perfectly well in 02.034:
They moved to a clump of trees, and though it was drier under them, the wind shook the rain off the leaves, and the drip, drip, was most annoying.
The fact that the sound is annoying has earned it the “low” tag.
- 02.029 his hood was dripping into his eyes,
- 02.034 and the drip, drip,
- 02.034 and the drip, drip,
- 04.046 with the sweat dripping
- 05.010 drops drip-drip-dripping from an unseen roof into the water below;
- 08.046 and there the drip of it
- 08.046 and waiting for a chance drip to fall
- 09.062 and that appealed to him with his dripping
- 09.063 and the trail of drippings that he left wherever he went or sat;
- 09.064 He was no longer dripping but he felt cold all over.
Update: Our commenter Sarah Hartman has generously provided us with a link to her thesis on such words!
“drip, n.” OED Online. Oxford University Press, March 2015. Web. 27 May 2015.
“drip, v.” OED Online. Oxford University Press, March 2015. Web. 27 May 2015.
words that you were saying 
I would tend to argue that while “drip” on its own isn’t strictly onomatopoetic, Tolkien is using it onomatopoetically in the “drip, drip” line. Onomatopoeia is often reduplicative. (If you want way more about this than you ever wanted to know, this was much of my undergrad thesis, so I have many, many sources on sound symbolism rattling around somewhere.)
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Sarah, yes! Do you have an electronic copy of that thesis somewhere you could link to? Sounds fabulous and just what we’re looking for!
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I will look!
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