You know there are words that we say that are actually comprised of other words? They are called Acronyms. There are some that most people know, like ATM (Automated Teller Machine) or PIN (Personal Information Number). Then there are others that people use all the time without knowing that they are actually acronyms.
The ones below are just a few examples. Please add any that have been missed.
NATO North Atlantic Treaty Organization
LASER Light Amplification by Stimulated Emission of Radiation