Cupro, or cupro rayon, is a regenerated cellulose produced by treating cotton cellulose with copper oxide. Cupro has similar properties to viscose but can have a softer feel and better-wicking properties. Bemberg is a brand name that used the cupro method.
Source
Sewport – What is Cupro Fabric – Properties, How its Made and Where 
December 2023, TÄNKOM | Revised May 2024 RETHINK
