This word is not acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

n. A room or environment that is controlled in such a way as to minimize airborne particulate matter, typically for the purpose of fabricating sensitive electronic or other devices.

"Formal software engineering processes, such as cleanroom engineering, are gradually finding rigorous, provable methods for software development."