(found in a list compiled by one of my kids, cross referenced to the relevant page number in Roald Dahl's "Matilda")
gormless
toddle
diddled
rakish
throttling
asinine
formidable
obstinate
piffle
regale
aimiably
blancmange
parabola
clot
brigand
suppurating
implacable
replete
comatose
swot
Gawd I love Roald Dahl. How could you read that list and not want to know what the book was about? (Sadly, this is exactly the sort of language that tends to be lost in the "abridged" books all to frequently passed off to children -- if you have a few minutes to spare, there is a brilliant reflection on abridged children's literature here.)