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

Opening the case, prosecutor Naeem Valli said Connolly also sent a message saying she intended to work her notice period as a childminder "on the sly" - despite being de-registered.

From BBC • Oct. 17, 2024

He was paroled from detention but banned from work and national health insurance, though he worked on the sly until about eight years ago, when the government started to tighten controls over parolees.

From Los Angeles Times • Jul. 24, 2023

You started taking hormones kind of on the sly for a couple of weeks before you even talked to your wife.

From Slate • Jun. 2, 2023

Do my thoughts trade places like letters, on the sly?

From "Bronx Masquerade" by Nikki Grimes

on the sly

Example Sentences

Related Words