raw fibers; minute fibers
Technical term used in materials science, textiles, and biology for unprocessed or very fine fibers.
この素材は原繊維の状態で輸入される。
This material is imported in the form of raw fibers.
顕微鏡で見ると、原繊維が絡み合っているのがわかる。
Under a microscope, you can see the minute fibers intertwined.
Compound of 原 (gen, 'original, raw') and 繊維 (sen'i, 'fiber'). The exact historical derivation is uncertain, but the term is a straightforward technical coinage.