Mis·chie·vous a. Causing mischief; harmful; hurtful; -- now often applied where the evil is done carelessly or in sport; as, a mischievous child. “Most mischievous foul sin.”
This false, wily, doubling disposition is intolerably mischievous to society. --South.
Syn: -- Harmful; hurtful; detrimental; noxious; pernicious; destructive.
-- Mis*chie*vous*ly, adv. -- Mis*chie*vous*ness, n.
adv : in a disobedient or naughty way; "he behaved badly in
school"; "he mischievously looked for a chance to
embarrass his sister"; "behaved naughtily when they had
guests and was sent to his room" [syn: badly, naughtily]