Frightful
frightful, ferocious, merciless, ...
"Boulevard" is a 9-letter word that means a wide street typically lined with trees.
The word you are looking for is "elucidate."
relevance
untouched
CHRONICLE
A 9-letter word that means "can be divided by" is "divisible."
Evaporate
imminence, necessity
dexterity
energetic
Alleviate.