Definition of "Dog" :

noun: a member of the genus Canis (probably descended from the common wolf) that has been domesticated by man since prehistoric times; occurs in many breeds

"The dog barked all night."

noun: metal supports for logs in a fireplace

noun: a hinged catch that fits into a notch of a ratchet to move a wheel forward or prevent it from moving backward

noun: a smooth-textured sausage of minced beef or pork usually smoked; often served on a bread roll

noun: someone who is morally reprehensible

"You dirty dog."

noun: informal term for a man

"You lucky dog."

noun: a dull unattractive unpleasant girl or woman

"She's a real dog."

verb: go after with the intent to catch

"The dog chased the rabbit."