In the context of cryptocurrencies, a Memecoin is a coin or token based on an internet meme or viral joke. While some Memecoins may also have real world use cases, the majority of Memecoins are simply based on the underlying meme used as a marketing strategy to promote the particular crypto project. In 2021, the most famous Memecoin is Dogecoin (DOGE).
For differentiation, see also Shitcoin.