fibre
noun
UK uk/ˈfaɪbər/ us( US fiber) [ C or U ]
a thread-like part made from plants or artificial material which can be made into products:
Natural fibres such as cotton tend to be cooler.
artificial/man-made/synthetic fibre(s)
They use lightweight carbon fiber for auto bodies.
The data-carrying capacity of a strand of optical fibre is doubling every year.