Spite, ill-will, bad faith or indirect motive.
In the context of defamation on the defence of qualified privilege, the Court will look for an indirect motive or ulterior purpose that conflicts with the sense of duty or the mutual interest which the occasion created, or dishonesty or reckless disregard for the truth.
In ATU v ICTU, Justice Lutz of the Alberta Court of Queens Bench used these words:
"Malice may be shown either from the nature, character and relevance of the words used or from evidence as to the behaviour, motive and knowledge of the defendant when publishing them, or in defending the action, or in failing to take appropriate steps in correcting, retracting or apologizing for the defamatory remarks.
"I note that while the burden of proving malice is normally on the plaintiff, in certain circumstances, the affirmative evidence of malice may be sufficiently cogent to require the Defendant to answer it or stand condemned.
"There are a number of factors that can indicate the presence of malice. For example, malice can be found where the published statements are false, and are known to be false by the Defendant. In addition, the conduct of the parties, or the manner of use of the words can indicate the presence of malice. In addition, malice may be shown by the constant repetition of the same or similar remarks.... The evidence is admissible even though the subsequent words may be independently actionable."
In libel and slander, malice is different from "irrationality, stupidity or obstinacy" (Turner v. Metro Goldwyn Mayer Pictures Ltd. 1950 1 All ER 449).
References:
Taylor v. Despard, 1956 OR 963 (CA)
Netupsky v. Craig, [1973] SCR 55
Cherneskey v. Armadale Publishers Ltd., 1979 1 SCR 1067
ATU v ICTU 195 Alberta Reports 161