The traditional currency we use every day can be broken down into cent, so for bitcoin there is also its smallest unit, satoshi. How small is satoshi? 1 satoshi = 0.00000001 BTC.
In October 2019 satoshi, bitcoin's smallest unit, was added to the Oxford English Dictionary. This is the latest addition to the famous English vocabulary, and it's part of the encryption industry's terminology, but it's not the first. In 2013, the OED added the word "bitcoin" defining it as "a digital currency that can be traded without a central bank".