Hello. I need some help with translation. At the moment I am reading short norwegian stories. One is called "Pleksi" and I don't know what does this word means. It's very difficult to understand this sentence "Vinduet i flykabinen er lite, ovalt, men ikke rundt, nærmere noe firkantet, dobbelt glass, pleksi, og det vil kreve en viss anstrengelse for å klare å ødelegge det." Can you help me to translate it?