| insidiously(quietly, secretly, personally, privately, furtively) |
| intimately(quietly, secretly, personally, privately, furtively) |
| obscurely(quietly, secretly, personally, privately, furtively) |
| on the QT(expression, idiom, clandestine, quietly, secretly) |
| on the quiet(expression, idiom, clandestine, quietly, personally) |
| on the sly(expression, idiom, clandestine, quietly, personally) |
| privily(quietly, secretly, personally, privately, furtively) |
| quietly(secretly, personally, privately, furtively, slyly) |
| slyly(clandestine, quietly, secretly, personally, privately) |
| stealthily(clandestine, quietly, secretly, personally, privately) |
| surreptitiously(clandestine, quietly, secretly, personally, privately) |
| under the table(expression, idiom, quietly, secretly, personally) |
| under wraps(expression, clandestine, secretly, slyly, underhandedly) |
| undercover(clandestine, secretly, furtively, slyly, underhandedly) |
| underhandedly(clandestine, quietly, secretly, personally, privately) |
| unobserved(quietly, secretly, personally, privately, furtively) |
| wildcat(clandestine, secretly, furtively, slyly, underhandedly) |
| a huis clos |
| clandestine(secretly, slyly, underhandedly, surreptitiously) |
| curtain |