From The Collaborative International Dictionary of English v.0.48:
Bast \Bast\, n. [AS. b[ae]st; akin to Icel., Sw., Dan., D., & G.
bast, of unknown origin. Cf. Bass the tree.]
1. The inner fibrous bark of various plants; esp. of the lime
tree; hence, matting, cordage, etc., made therefrom.
[1913 Webster]
2. A thick mat or hassock. See 2d Bass, 2.
[1913 Webster]