a treacherous person, especially one who feigns friendship.
a concealed danger.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use snake in the grass in a sentence
She was an old snake-in-the-grass, too,—to use one of Papa's expressions.Rough-Hewn | Dorothy Canfield
Other Idioms and Phrases with snake in the grass
A treacherous person, as in Ben secretly applied for the same job as his best friend; no one knew he was such a snake in the grass. This metaphor for treachery, alluding to a poisonous snake concealed in tall grass, was used in 37 b.c. by the Roman poet Virgil (latet anguis in herba). It was first recorded in English in 1696 as the title of a book by Charles Leslie.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.