Blockchain

A decentralized digital ledger that records all transactions across a network of computers. Known for its security and transparency, it's the underlying technology behind cryptocurrencies like Bitcoin. The blockchain's distributed nature makes it resistant to hacking, forging, or altering.
In a broader, casual context, "blockchain" might also refer to something complex and trendy that's often dropped in conversations to sound tech-savvy, whether or not it's entirely understood.

"With the rise of cryptocurrencies, the blockchain technology is revolutionizing the way we think about financial transactions."
"Dude, I have no idea what you just said, but you dropped 'blockchain' in there, so you must be on the cutting edge of tech!"