-lē, -li adjective
: treacherously cowardly
the dastardly brute had trampled on him when he could not turn against him — Anthony Trollope
: insidiously or despicably mean
the flood waters have done many dastardly things to our residents — K.K.Coleman
: base
choosing the safe side … appeared to me to be playing a rather dastardly part — George Borrow
Synonyms: see cowardly