Definition of rainbow trout
: a large stout-bodied salmonid fish (Oncorhynchus mykiss syn. Salmo gairdneri) of western North America that is related to the Pacific salmon and is typically greenish above and white on the belly with a pink, red, or lavender stripe along each side of the body and with profuse black dots — compare steelhead
Learn More about rainbow trout
Britannica.com: Encyclopedia article about rainbow trout
Seen and Heard
What made you want to look up rainbow trout? Please tell us where you read or heard it (including the quote, if possible).