Thirdly used in a sentence

Thirdly in a sentence as an adverb

Because, thirdly, it hinders design, it's very easy to code yourself into a corner in the name of passing a test-suite. Related to the design issue is a simple fact of laziness.

First, it's an industry that's been plummeting for a decade, secondly, the entire recording industry is worth about that much, and thirdly, the entire concept of making money from copyrighted works of art is under threat. This theory doesn't hold water, sorry.