Full Idea
Wide content is derivative, a product of narrow content and relationships of acquaintance with external things.
Clarification
'Wide' content is meaning which depends on how the world is, not on a mental state
Gist of Idea
Wide content derives from narrow content and relationships with external things
Source
David Lewis (Lewis: reduction of mind (on himself) [1994], p.430)
Book Reference
'A Companion to the Philosophy of Mind', ed/tr. Guttenplan,Samuel [Blackwell 1995], p.430
A Reaction
I would say: content is a mental state, but it is created and fixed by a community, and wide content is the part fixed by experts in the community. We can all be wrong about meanings, and occasionally most of us are wrong about a specialised meaning.