on the sly
1
in a manner that is inclined to conceal a person's actual feelings and intentions
The idiom "on the sly" originated from the word "sly," which means cunning or crafty. The phrase refers to doing something secretly or discreetly, without others' knowledge or approval. It is used to convey a sense of stealthiness or furtiveness in one's actions, often implying that the activity being discussed is meant to be concealed or kept hidden from others' awareness.
- She ate the last piece of cake on the sly, hoping no one would notice.
- The employees would often take extended breaks on the sly, trying to avoid their supervisor's attention.
- He bought a gift for his partner on the sly, planning to surprise them on their anniversary.
- The teenager snuck out of the house on the sly to attend a late-night party.
- The spy acquired classified information on the sly, carefully avoiding detection by enemy agents.
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