滴形容圆，比如一滴水 溜是动词，参考溜冰，能溜得起来就表示表面很光滑 所以，滴溜形容很圆。 他的门滴溜滚圆。可能是：他的门（框）是圆形的。

This is a Chinese translation from the English original of J.R.R. Tolkien's Lord of the Rings. For the correct English version of this sentence,, you should search the original novel. It is never a good idea to put forward a Chinese translation of an English original and ask nembers here to translate it into English, for obvious reasons. It also undermines the credibility of your questions, because members will think that you are being disingenuous and trying to play a game to trick them into rendering an English version that is different from the original, and they will look stupid. Nobody tries to rewrite Tolkien and there is no need to trick people into doing so.

Although I don't enjoy re-translation back and forth.... Here is Baidu: 滴溜溜 = going round and round; revolving or flowing; with your 滴溜 either emphasizing the 滚圆 roundness, or indicating a revolving door. I'd say the latter.

This is the English original, written by J.R.R.Tolkien: "It had a perfectly round door like a porthole, painted green, with a shiny yellow brass knob in the exact middle." "怎么翻译成英语? " 不用"翻译"吧，它本来就是英语原著。