Without any technical jargons, cryptocurrency can simply be referred to as digital or virtual money.
However, a more complicated and accurate answer is that:
A cryptocurrency is a digital asset designed to work as a medium of exchange. It uses strong cryptography to secure financial transactions, control the creation of additional units, and verify the transfer of assets. Cryptocurrencies enjoy decentralized control in comparison with centralized electronic money and central banking systems. The decentralized control of each cryptocurrency works through a distributed ledger technology, popularly known as a blockchain; which serves as a public financial transaction database.