It is an adjective.
Meaning: meaning or meant to do harm.It is used when someone or something is intended to do harm i.e vicious in character .
Root of the word : mal means bad, malicious, malign, malice, malignant, malodorous, malevolence, malady, anomalous, maladroit
maliciously - adverb
maliciousness - noun
Synonyms : wicked, mean, spiteful, nasty, cruel,vengeful,awful,green-eyed,resentful
Antonyms : kind
1)The malicious man beat up the children playing near his house.
2)The children are again with their malicious mischief.
3)The malicious gossip has no end.
4)My computer is attacked by a malicious program.