nelly
Synonym discussion
Sense: noun/1
All four expressions reject an idea, but they differ in tone. 'Absolutely not' is the broadest and can fit both speech and careful writing when you need a firm answer. 'No way' is informal and current, often showing surprise as well as refusal. 'Not a chance' is also spoken and strong, but it sounds more neutral than slangy. 'Over my dead body' is the most dramatic and suggests active resistance, not just a negative answer. 'Not on your nelly' is the most old-fashioned and strongly British of the group, so it feels colorful rather than neutral. Compare: a manager might write 'Absolutely not', a friend might say 'No way', and a stubborn parent might shout 'Over my dead body'.
Etymology
The refusal phrase 'not on your nelly' is usually explained as a shortened piece of British rhyming slang. It is often linked with 'Nelly Duff', which rhymed with 'puff', meaning breath or life, so the phrase originally suggested something like 'not while I still have breath in me'.
First known use
1823
1823, in the meaning defined at sense 1 Adjective