A generic term for acrylic fibers composed of a long chain synthetic polymer containing 35-85% of acrylonitrile units such as Dynel and Verel. See: R. W. Moncrieff, Man-Made Fibres (Wiley, New York, 4th ed., 1963) p 9. Review: Kennedy in Encyclopedia of Polymer Science and Technology vol. 8, N. M. Bikales, Ed. (Interscience, New York, 1968) pp 812-839.