Fe*lo"ni*ous (?), a. Having the quality of felony; malignant; malicious; villainous; traitorous; perfidious; in a legal sense, done with intent to commit a crime; as, felonious homicide.

O thievish Night,
Why should'st thou, but for some felonious end,
In thy dark lantern thus close up the stars?

-- Fe*lo"ni*ous*ly, adv. -- Fe*lo"ni*ous*ness, n.