Definition - What does Bitcoin Core mean?
Bitcoin Core is a digital successor or “reference client” of the bitcoin cryptocurrency that is now traded all over the world, though its legality varies based on jurisdiction. Bitcoin Core represents the succession from Bitcoin to Bitcoin QT and then on to Bitcoin Core. Alternately, Bitcoin Core is a separate project from various other divergent bitcoin projects developed through hard and soft forks, including Bitcoin Classic, Bitcoin Cash, Bitcoin XT, Bitcoin Unlimited and LiteCoin.
Techopedia explains Bitcoin Core
The developers of the Bitcoin Core community are careful to distinguish Bitcoin Core from other projects. In some cases, changes are backward-compatible, but with other changes, the bitcoin network gets split, and a separate community must maintain a separate chain.
Another way to define Bitcoin Core is that it “validates the entire blockchain” as a direct succession of the original Bitcoin project developed by Satoshi Nakamoto and others. As the central branch of bitcoin, this digital cryptocurrency uses wallets and is traded according to established models throughout the Bitcoin Core community. Further changes are announced and debated among bitcoin users, miners and other parties.