Any cryptocurency which is not an industry leading coin.
A coin which is an alternative to the leading coin.
Altcoins typically have volatile prices and can be a great way to earn - or lose - a lot of value fast.
1.1 - Example
For each sector, an altcoin could be any except...
Store of value: Bitcoin (BTC)
Smart contracts: Ethereum (ETH)
Peer-2-peer cash: Bitcoin Cash (BCH)
Every cryptocurrency that is not Bitcoin (BTC).
* All terms and definitions may update as the Cryptionary improves.