a large, harmless rat snake, Elaphe guttata guttata, of the southeastern U.S., having yellow, tan, or gray scales with dark-red blotches: once common in cornfields but now an endangered species.
Origin of corn snake
An Americanism dating back to 1670–80
Also called red rat snake.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019