Full Idea
It was important to Kripke to contrast the rigidity of names with the non-rigidity of many or most definite descriptions.
Gist of Idea
Names are rigid, making them unlike definite descriptions
Source
report of Saul A. Kripke (Naming and Necessity lectures [1970]) by Mark Sainsbury - The Essence of Reference 18.6
Book Reference
'Oxford Handbook of Philosophy of Language', ed/tr. Lepore,E/Smith,B [OUP 2008], p.418
A Reaction
Philosophers always want sharp distinctions, but there are tricky names like 'Homer' and 'Jack the Ripper' where the name is stable, but its referent wobbles.