on-the-sly
Behind closed doors
Done secretly or covertly, especially to avoid detection or disapproval.
The phrase often implies sneakiness or mild deception: She's been smoking on the sly, He ate cookies on the sly while dieting.
Sometimes suggests a hidden affair or illicit activity: They'd been seeing each other on the sly for months.
Intentionally concealed
- stealthySecretly cautious in movement
- sneakyStealthily deceptive
- furtiveSecretive and sly
- clandestineConcealed from authorities
undercover · hush-hush · discreet · hidden · concealed · surreptitious · undetected · incognito
Prohibited by law
- prohibitedOfficially not permitted
- contrabandProhibited trade goods
- bootlegIllegally produced goods
- smuggledMoved goods illegally
unauthorized · banned · taboo · illegal · unlawful · black-market · moonshine · speakeasy
Deceptive rule-breaking
- dishonestInclined to deceive
- duplicitousDeliberately deceptive in nature
- two-facedInsincere and deceptive
- underhandedSecretly dishonest or unfair
cunning · scheming · conniving · treacherous · deceitful · fraudulent · misleading · swindling
covert
Intentionally concealed
clandestine · undercover · hush-hush · discreet · hidden · concealed · surreptitious · undetected · incognito · under-the-table
illicit
Prohibited by law
- prohibitedOfficially not permitted
- contrabandProhibited trade goods
- bootlegIllegally produced goods
smuggled · unauthorized · banned · taboo · illegal · unlawful · black-market · moonshine · speakeasy · underground
cheating
Deceptive rule-breaking
- dishonestInclined to deceive
- duplicitousDeliberately deceptive in nature
- two-facedInsincere and deceptive
underhanded · cunning · scheming · conniving · treacherous · deceitful · fraudulent · misleading · swindling · double-dealing
on-the-slyopenly
Without hiding anything
in the open · publicly · out in the open · overtly · in plain sight
on-the-slyofficially
With authorized sanction
by the book · legitimately · sanctioned · on the record · with approval
on-the-slyaboveboard
Honest and unconcealed
on the level · honestly · transparently · straightforwardly · candidly