covert
KOH-vurtadjMeaning secret; not openly shown or done
Memory hook COVERed: kept under COVER. Behind the sofa, under a blanket, the cousins whisper their plans for Mom’s surprise party; the whole plan is kept under cover, covert.
Lila shot a covert glance at the clock, hoping the teacher would not notice.
In context The surprise party was a covert operation: invitations were passed in whispers, and the guest of honor never suspected a thing.
Similar secret, undercover, hidden, secretive
Opposite overt, open, public
From Old French covert, “covered,” from covrir (to cover).