Definitions

on the sly

ADJECTIVE

subterrestrial

Synonyms

WEAK

alternative avant-garde clandestine concealed covert experimental hidden hush-hush hypogeal hypogean hypogeous on the Q.T. private radical resistant resistive revolutionary subterranean surreptitious unbowed unconventional under wraps undercover unusual

ADJECTIVE

surreptitious

Synonyms

STRONGEST

clandestine covert furtive hush-hush unauthorized

WEAK

fraudulent hidden hole-and-corner on the Q.T. private skulking slinking sly sneaking stealthy sub-rosa under wraps under-the-table undercover underhand veiled

Antonyms

STRONGEST

aboveboard forthright honest open public truthful

WEAK

authorized

ADJECTIVE

underground

Synonyms

STRONGEST

clandestine experimental hidden private

STRONG

alternative avant-garde covert radical revolutionary

WEAK

concealed hush-hush on the Q.T. resistant resistive surreptitious unbowed unconventional under wraps undercover unusual

Antonyms

STRONGEST

open

STRONG

conservative

WEAK

aboveground authorized condoned ground known legal public sky

ADVERB

covertly

Synonyms

STRONGEST

clandestinely secretly surreptitiously

WEAK

by stealth furtively hush-hush in camera in holes and corners on the Q.T. on the quiet privately slyly stealthily sub-rosa under wraps undercover wildcat

Antonyms

WEAK

candidly frankly honestly openly overtly publicly

ADVERB

secretly

Synonyms

STRONGEST

clandestinely covertly furtively personally privately quietly stealthily surreptitiously

WEAK

behind closed doors behind someone's back by stealth confidentially hush-hush in camera in confidence in holes and corners in secret in strict confidence insidiously intimately obscurely on the Q.T. on the quiet privily slyly sub-rosa under the table underhandedly unobserved

Antonyms

STRONGEST

publicly

WEAK

openly

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

The math-proficiency analysis suggests it may be doing so on the sly.

From The Wall Street Journal • Nov. 30, 2025

You steal work from US writers on the sly, and you're blacklisted.

From Los Angeles Times • May 2, 2023

Sometimes, developers bought up units on the sly, knowing that control over assessments and expenditures could come as soon as a majority.

From Slate • Aug. 4, 2021

When Burnett was growing up in Brooklyn, dancing was something he had to do on the sly.

From New York Times • Jul. 23, 2021

“Nothing,” Mom says, and continues scraping, but I see her steal a smile on the sly.

From "Wayward Creatures" by Dayna Lorentz

on the sly

Example Sentences

Related Words