furtive

Of a thing: done with evasive or guilty secrecy.

[…] The Defendant never vvas acknovvledged by the Sieur Harrouard’s Family, nor by that of his VVife. Thus, granting him to have been in Poſſeſſion of his Son’s Eſtate, it vvould only be a furtive and clandeſtine, not a public and avovved Poſſeſſion; and conſequently ſuch a Poſſeſſion as is incapable of founding a juſt and legal Title.

[T]ender cares and mild domestic Loves, / With furtive watch, pursue her [a swan] as she moves; […]

Of a thing: that has been acquired by theft; stolen; also (generally) taken stealthily.

Novv ſhine theſe Planets vvith ſubſtantial Rays? / Does innate Luſtre gild their meaſur'd Days? / Or do they (as your Schemes, I think, have ſhovvn) / Dart furtive Beams, and Glory not their ovvn, / All Servants to that Source of Light, the Sun?

Of a person or an animal: sly, stealthy.

All women have their foibles. Wise husbands must bear and forbear. Is that all? wherefore, then, is her aspect so furtive, wherefore on his a wild, vigilant sternness?

So, Riderhood looking after him as he went, and he with his furtive hand laid upon the dagger as he passed it, and his eyes upon the boat, were much upon a par.

Of a person, etc.: inclined to steal; pilfering, thieving.