Synthetic Fibers
noun
Fibers that have been changed from other materials are synthetic fibers. They aren't natural because they were something else once. Like plastic, or kittens.
Note that this is an abbreviation of the specialist term 化学繊維, and it mostly comes up in industrial contexts.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
掃除には、化繊箒を使っています。
I use a synthetic fiber broom for sweeping.