Words used to mean their opposites

"Is there a word in the English language that more reliably means its opposite than ‘amicable’?

Twitter responses included: “moot,” “humbled,” “nice,” “my friend,” “nonplussed,” “cordial,” “priceless,” “tolerance,” “literally,” “spry,” “sincerely,” “honest,” “pal,” “sure,” and “Fine” particularly when given as a one word answer.”

Tyler Cowen's favourite is "spry". "Respectfully" was the one that came to mind for me, and gets a mention in the comments.