Distro

In the Linux world, there are hundreds of different flavors of distro. Examples include Debian, Ubuntu and Red Hat (among many others). When referencing a Linux OS, administrators usually ask questions like: Which distro does the application sit on top of? or Which distro are you using?

Technically, a distribution is any deployment of software and isn't specifically Linux. Usually in this case you'll hear it referred to as a "distribution of software." Despite this, the term "distro" is nearly always used in a Linux context. So, while a distribution of software is a generic term for any bundle of software, distro is nearly always a flavor of Linux.