Iteration

Iteration can be a verb or a noun. For the noun, you would refer to something as "an iteration". If you created a computer program, this would be the first iteration (noun) of your project. If you tested that program, improved it based on feedback, the next version of your program would become the 'second iteration (noun)'. If you tested that program and improved it, the next version becomes the 'third iteration (noun)'. This is what is called an iterative process; the action you are taking is also called "iteration" (verb). You don't need to describe whether you are using the word iteration as a verb or a noun - the context of your language will determine that.