Exceptional = extraordinary, remarkable, unusual.
- Shaun is an exceptionally intelligent student.
- Such loans will be granted only in exceptional cases.
- Vaikom Vijayalakshmy is a gifted and exceptionally talented singer.
- He has a garden with exceptional beauty.
- Modifications in the original plan can be sanctioned only in exceptional cases.
Exceptionable = objectionable, causing disapproval or offence.
- His recent writings on individual freedom are highly unpleasant and exceptionable.
- You should be careful not to seem exceptionable in your language and manners.
- Their exceptionable remarks may arouse religious sentiments and that may disrupt the otherwise calm social atmosphere.