Just as fruition and evergreen are words that bring forth hope, there can probably be no better word for despair than rancid. The way it rolls off the tongue - you can even curl the tongue to make the initial sound - in such a burst of awfulness.
This word is so powerfully horrible that I don't really think anyone uses it in speech. They write it a lot, but when was the last time you heard someone speak of something (other than food) that was rancid?