snake in the grass

noun

1. a treacherous person, especially one who feigns friendship.
2. a concealed danger.

Word History and Origins

Origin of snake in the grass¹

First recorded in 1690–1700

Idioms and Phrases

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.

Example Sentences

She was an old snake-in-the-grass, too,—to use one of Papa's expressions.

From Project Gutenberg