1. a mean, sneaking coward.
2. of or befitting a dastard; mean, sneaky, and cowardly.
dastard (n.), dastardly (adj.)
A dastard was once a coward, but today the noun is rare and means simply "an unprincipled, treacherous villain.”
The adjective means "sneaky, underhanded, and treacherous, and in those meanings still echoes the original sense.
Today it’s a word rather hard to take seriously.
A prototypical Agatha Christie adaptation, Death on the Nile is a classic mystery with an all-star cast of recognizable names and faces. Continuing in the vein of Murder on the Orient Express, a murder has occurred during a river cruise, making everyone onboard a suspect, and, as the eminent detective Hercule Poirot observes, everyone had either an opportunity or a motive to do the dastardly deed.
But who will be brave enough to contact George Clooney, or Denzel Washington, and propose them for the role of a wuss?