Definition of red dog:
(n) :
(countable, US, American football) A blitz.
(v) :
(US, American football) To blitz.
(n) :
(uncountable) The lowest grade of flour in milling, secured largely from the germ or embryo and adjacent parts, and mainly useful as animal feed.
(n) :
(uncountable) Coal slag.
(n) :
(uncountable, informal) Prickly heat; miliaria.
(n) :
Used other than figuratively or idiomatically: see red, dog.