Full Idea
Common words, even proper names, are usually really descriptions; that is, the thought in the mind of a person using a proper name correctly can generally only be expressed explicitly if we replace the proper name by a description.
Clarification
'Proper names' label individuals, such as 'Bertrand Russell'
Gist of Idea
Proper names are really descriptions, and can be replaced by a description in a person's mind
Source
Bertrand Russell (Problems of Philosophy [1912], Ch. 5)
Book Reference
Russell,Bertrand: 'The Problems of Philosophy' [OUP 1995], p.29
A Reaction
This is open to challenge, and the modern idea is that they are more like baptisms, but it all comes down to the debate about internal and external content. Russell would appear to be voicing the internalist theory of names.