Bitcoin (n.):
1. A decentralized internet crypto-commodity minted, authenticated and exchanged by its users.
2. The distributed, freely accessible internet ledger with the bitcoin(1) (or the satoshi) as the unit of account.
3. The community of Bitcoin(2) miners, node operators, developers, users, merchants, and exchanges. The Bitcoin(2) ecosystem.
This is a good point - "Bitcoin" means more than one thing. Actually, I believe def. 1 is small-b "bitcoin".