Using "library" instead of "engine".

README.md

 three.js
 ========
 
-#### Javascript 3D Engine ####
+#### Javascript 3D library ####
 
-The aim of the project is to create a lightweight 3D engine with a very low level of complexity — in other words, for dummies. The engine can render using <canvas>, <svg> and WebGL.
+The aim of the project is to create a lightweight 3D library with a very low level of complexity — in other words, for dummies. The library provides <canvas>, <svg> and WebGL renderers.
 
 [Contributors](http://github.com/mrdoob/three.js/contributors) — [Getting Started](http://www.aerotwist.com/lab/getting-started-with-three-js/) — [API Reference](http://github.com/mrdoob/three.js/wiki/API-Reference)