Strong fiber is a type of material that is used for a variety of purposes, such as making rope, fabric, and paper. The four crossword solutions for the term strong fiber are SISAL (5 letters), RAMIE (5 letters), BAST (4 letters), and istle (5 letters). SISAL is a type of agave plant that is native to Mexico and Central America and is used to make rope and twine. RAMIE is a type of perennial herbaceous plant that is native to Asia and is used to make fabric. BAST is a type of fiber that is obtained from the inner bark of certain trees and is used to make paper and fabric. Istle is a type of fiber that is obtained from the leaves of certain plants and is used to make rope and twine.