| intimately(quietly, secretly, personally, privately, furtively) |
| irregularly |
| obscurely(quietly, secretly, personally, privately, furtively) |
| on the QT(expression, idiom, adverb, clandestine, quietly) |
| on the quiet(expression, idiom, adverb, clandestine, quietly) |
| privily(quietly, secretly, personally, privately, furtively) |
| quietly(noun, secretly, personally, privately, furtively) |
| sneakily(noun, adverb) |
| sub rosa(expression, adverb, clandestine, quietly, personally) |
| traitorously(adverb, dishonestly) |
| treacherously(adverb, dishonestly) |
| under the table(expression, idiom, quietly, secretly, personally) |
| under wraps(expression, adverb, clandestine, secretly, slyly) |
| undercover(adverb, clandestine, secretly, slyly, surreptitiously) |
| unfairly |
| unobserved(quietly, secretly, personally, privately, furtively) |
| wildcat(adverb, clandestine, secretly, slyly, surreptitiously) |
| by corrupt means(expression, idiom) |
| by lying(expression, idiom) |
| clandestine(adverb, secretly, slyly, surreptitiously) |