Slang One considered to have the dominant position or highest authority, especially as a result of a competitive victory.(noun)
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.
Use "top dog" in a sentence
"I had defended my title several times over the years, and once I became the top dog on the mixed martial arts scene, I brought fans down on both sides of Tito Ortiz."
"She led up to it by talking of her husband's ambition to build a church and hall over at Kowloong; even in those days it was the fashionable place, so he would be quite top dog among the local gospel-wallopers."