Both Uses

treacherous
in
The Hobbit
(Edited)

There it is: dwarves are not heroes, but calculating folk with a great idea of the value of money; some are tricky and treacherous and pretty bad lots; some are not, but are decent enough people like Thorin and Company, if you don't expect too much.
p. 196.4 *

treacherous = untrustworthy
Still elves are light-footed, and though they were not in these days much used to the marches and the treacherous lands between the Forest and the Lake, their going was swift.
p. 233.1 *

treacherous = dangerous

Definitions:

(1) (treacherous as in: the road is steep and treacherous)
dangerous -- often in a non-obvious way
(2) (treacherous as in: a scheming, treacherous assistant)
guilty of betrayal or deception or likely to betray or deceive
(3) (meaning too rare to warrant focus)