Perhaps you were looking for a word that your writer's genetic memory knew -but that you did not.
Folks, I've got the answer: The Phrontistery

The Phrontistery is a registery of old and forgotten English words that you can find in no modern (or even semi-ancient) dictionary.
Some of my favorites that I've discovered lately are:
Welmish –of a pale, sickly color
Empyreal -of, like or pertaining to heaven; sublime; skyward
Inocciduous –of a star, never setting
Nubivagant –moving through the clouds
And, for you classical poets out there:
Rhodologist –one who studies or classifies roses
(Remind me to rant about roses at a later date)

Anyway, I encourage the checking-outage of the website. If you want to go straight to the glossary, and are having a hard time finding it, here is the direct link:
The Phrontistery's Glossary by Letter