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Meaning of top dog

top' dog'

Pronunciation: [key]
  1. a person, group, or nation that has acquired a position of highest authority.
  2. the winner of a competition or rivalry; champion: He was determined to be top dog at the swimming meet.
  3. the alpha male or alpha female in a dominance hierarchy.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.