Principle of reversibility? (5)
I believe the answer is:
tenet
This could be a double definition.
'principle' is the first definition.
(a tenet is a principle or value)
'reversibility?' is the second definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'of' acts as a link.
Can you help me to learn more?
(Other definitions for tenet that I've seen before include "Key principle" , "Article of belief" , "Article of faith; doctrine" , "Canon" , "That's the law" .)