bast fiber

This term is primarily used in botanical, textile, and industrial contexts to describe a specific category of plant fibers. It is distinguished from leaf fibers (like sisal) or seed fibers (like cotton) by its origin in the phloem or inner bark of the plant stem.

Because it is a technical term, it is rarely encountered in casual conversation and is typically found in academic papers on materials science or historical texts regarding textile production.

In terms of usage, "bast fiber" is often used as a collective category. While the word "fiber" can be counted when referring to individual strands, in the context of industrial production and material classification, it frequently functions as an uncountable mass noun.