It's a slight stretch, but based on "Dwimmorberg" clearly meaning "Enchanted Mountain", "Haunted Mountain" or "Magic Mountain", we can see that "dwimmer" or "dwimmor" can be loosely interpreted as "magic", or "mystical". That part's easy. [Edit: Even easier than I thought! "Dimmer" is defined in English as a noun meaning "Magic, sorcery or spell".]
Some sources define a word in English "laik" as a verb meaning "to play" in the sense of not working, or not professional. Again, in English, it seems to be a cousin of the noun or adjective "lay" meaning non-professional or non-clergy. In several languages (Czech, Polish, and Serbo-Croation among them), "laik" directly means "non-professional" or "non-clergy".
Combining Tolkein's penchant for backwards-reverse-forwards etymological style of word creation, along with his pulling from Middle English ("lathspell" is a great example), along with the context (it totally fits Eowyn's character to boldly insult the Lord of the Nazgul), the best interpretation of "dwimmerlaik" seems to be "one who plays with magic, as a child with toys". Personally, I laugh when I read that part, because it's such a great insult for the Witch King of Angmar.
More Edit:
Now I'm on round two of researching this, and I came across this little gem:
Quote:
" laik (=corpse) is cognate with lych or lich, as in the lych-gate of a cemetery where coffins are sheltered before funerals."
But now I'm a little more happy with "play" because I think I got that from the OED one day:
Quote:
"-laik in 'dwimmerlaik' is derived from the ON leikr, cognate to OE la'c, both meaning 'to play', while the OE can also mean 'dance, ritual, or sacrifice'. It has no connection to words for body or corpse. [source: OED]
The compounds 'dwimmerlaik' and 'dwimmercraft' both mean illusion, an act of sorcery or magic, and jugglery (!). The last evokes an image of Sauron dressed in motley juggling pins or setting plates spinning atop rods. "
Just having this conversation means we're not only LoTR fans, we're total LoTR nerds! Yay?