Wiktionary
n. A dominant dog; a dog that is an alpha male or alpha female. ''Often used figuratively.''
Wikipedia
Alpha Dog is a 2006 American crime drama film written and directed by Nick Cassavetes, first screened at the Sundance Film Festival on January 27, 2006, with a wide release the following year on January 12, 2007. Starring Emile Hirsch, Justin Timberlake, Ben Foster, Shawn Hatosy, Anton Yelchin, Olivia Wilde, Amanda Seyfried with Harry Dean Stanton, Sharon Stone, and Bruce Willis, the film is based on the true story of the kidnapping and murder of Nicholas Markowitz in 2000.
Usage examples of "alpha dog".
The alpha dog lay beside the bitch, licking his front paws and, occasionally, his mate’.
It had been hard seeing them go, but Ray knew that there could be only one alpha dog to a pack, and Max had earned the right to head up his own team.
He was a big German shepherd, the alpha dog in Moth's pack, ninety pounds of goofy good humor that could turn instantly serious on a word from Moth.
It was early morning in Sunda, and she waded hip-deep in the crystal-clear waters of a river that flowed beneath the decaying hulk of an old warehouseor at least that was the illusion generated for her by the atrium of the alpha dog.