olemus
looduslik või tehislik peen niitjas moodustis

Wiktionary:
1. (countable) a single elongated piece of a given material, roughly round in cross-section, often twisted with other fibers to form thread
3. (textiles) a material whose length is at least 1000 times its width

piltlikult
https://duckduckgo.com/?q=natural+fibers&t=h_&iar=images&iax=images&ia=images

https://duckduckgo.com/?q=synthetic+fibers&t=h_&iar=images&iax=images&ia=images

näiteid
bast fiber -- niinekiud
flax fiber -- linakiud
glass fiber _-- klaaskiud
hemp fiber_ -- kanepikiud
microfiber -- mikrokiud
nerve fiber-- närvikiud
nylon fiber -- nailonkiud
optical fiber -- optiline kiud

ülevaateid
https://en.wikipedia.org/wiki/Fiber