Definition of "clandestine"
clandestine
adjective
comparative more clandestine, superlative most clandestine
Done or kept in secret, sometimes to conceal an illicit or improper purpose.
Quotations
Monimia, who while she yielded to his earnest entreaties had always felt, from the natural rectitude of her understanding, the impropriety of their clandestine correspondence, would, he feared, be more than ever sensible of her indiscretion, when she found that a servant was entrusted with it...
1793, Charlotte Smith, chapter 1, in The Old Manor House, volume 3
Wildeve's clandestine plan with her was to take a little gravel in his hand and hold it to the crevice at the top of the window shutter, which was on the outside, so that it should fall with a gentle rustle, resembling that of a mouse, between shutter and glass.
1878, Thomas Hardy, chapter 11, in The Return of the Native