Definition of "underhand" []

• Marked by or done in a deceptive, secret, or sly manner; dishonest and sneaky. See Synonyms at secret. (adjective)
• Sports Executed with the hand brought forward and up from below the level of the shoulder; underarm: an underhand pitch. (adjective)
• With an underhand movement: Throw the ball underhand. (adverb)
• In a sly and secret way. (adverb)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The head of Nato in Libya, Lieutenant-General Charles Bouchard, said Col Gaddafi's forces had employed what he called underhand and immoral tactics in their seven-week drive to dislodge the rebels from the city."
• "Taking that an 'putting it with the murder an' other funny things that's been happening about Mr. Sumner lately, it 'pears to me that something underhand is going on, he said with a deferential bow."
• "It was of course the law of the place that they were never to take no notice, as Mr. Buckton said, whom they served; but this also never prevented, certainly on the same gentleman's own part, what he was fond of describing as the underhand game."