Adaptive Web Design (AWD)

Adaptive websites adapt to the width of the browser at a specific points. In other words, the website is only concerned about the browser being a specific width, at which point it adapts the layout.

Moving Beyond the Responsive Web to the Adaptive Web
The Difference Between Responsive and Adaptive Design
CSS Tricks
Adaptive vs. Responsive Design
Interaction Design Foundation
Responsive vs adaptive webdesign, which is best for you?
Web Designer Depot
Mobile Websites: Mobile-Dedicated, Responsive, Adaptive, or Desktop Site?
Nielsen Norman Group