Antonyms of adv harmlessly

1 sense of harmlessly

Sense 1
harmlessly -- (in a harmless manner; "this is a harmlessly childish game")
       Antonym of harmfully (Sense 1)
      => detrimentally, harmfully, noxiously -- (in a detrimental manner)

Synonyms of adv harmlessly

1 sense of harmlessly

Sense 1
harmlessly -- (in a harmless manner; "this is a harmlessly childish game")