Alpha male (or female)

Who uses it: Animal behaviorists
What it means: In a group of social animals, the one who leads. Some groups of animals, such as wolf packs, may have an alpha pair, male and female. The alpha male is often the strongest and best fighter, but not always; among the bonobo monkeys, for example, the alpha male is the wiliest.
How you can use it: In any group activity.

Dizzy is the opposite of an alpha dog. Faced with almost any other dog, of any size, he defers almost immediately. But Lucy, a tiny Boston terrier, starts her day during my visits by jumping on my pillow and licking my face -- and Dizzy moves to block her, apparently because he is the only dog allowed to lick my face. Thank goodness, he doesn't do that very often. I love my dog, but I can wash my own face.