·adj Prosecuted with careful attention and effort; careful; painstaking; not careless or negligent.
II. Diligent ·adj Interestedly and perseveringly attentive; steady and earnest in application to a subject or pursuit; assiduous; industrious.
Double diligent, like the Devil's apothecary; said of one affectedly diligent. ...
Dictionary of The Vulgar Tongue by Francis Grose