[c]/ˈægənaɪz / (say 'aguhnuyz)

verb (agonised, agonising)
verb (i)
1. to suffer anxiety in the process of making a difficult decision or choice.
2. to make great effort of any kind.
3. Obsolete to writhe with extreme pain; suffer violent anguish.
verb (t)
4. Obsolete to distress with extreme pain; torture.
5. agonise over (or about), to worry excessively about.
Also, agonize. {Medieval Latin agōnizāre, from Greek agōnizesthai contend}
agonising, adjective
agonising, noun
agonisingly, adverb
agonisedly /ˈægənaɪzədli/ (say 'aguhnuyzuhdlee), adverb

Australian English dictionary. 2014.