excruciating
extremely painful; agonizing
crux
the most important or decisive point
crucial
necessary; essential
indolent
lazy; averse to work
doleful
sad; mournful
dolorous
mournful; gloomy
acerbic
harsh and biting in tone
acrid
stinging or biting in odor or taste; irritating
acrimonious
exhibiting harsh sharpness in speech or mood
exacerbate
to make worse or more severe
fervent
passionately excited or enthusiastic
fervor
emotional excitement; heated enthusiasm
effervescent
highly spirited; animated