Antiquated perjorative, but etymology interesting.
Dastard (Page: 367)
Das"tard (?), n. [Prob. from Icel. dęstr exhausted. breathless, p. p. of dęsa to groan, lose one's breath; cf. dasask to become exhausted, and E. daze.] One who meanly shrinks from danger; an arrant coward; a poltroon.

You are all recreants and dashtards, and delight to live in slavery to the nobility. Shak.