Lewis & Short

furtim, adv. [fur; hence, like a thief, i. e.], by stealth, secretly, privily (rare but class.; cf.: clam, clanculum, furtive): at enim hic clam furtim esse volt, ne qui sciant, Plaut. Poen. 3, 3, 49: sine lictoribus profectum clam furtim, etc., Liv. 21, 63, 9: ut furtim tota decemviris traditur! Cic. Agr. 2, 16, 41: quae (lagenae) furtim essent exsiccatae, Q. Cic. ap. Cic. Fam. 16, 26, 2: alterum genus est imitatione; admodum ridiculum, sed nobis tantum licet furtim, si quando, et cursim, Cic. de Or. 2, 62, 252: (Janua) neu furtim verso cardine aperta sones, Tib. 1, 2. 10: quid juvat, immensum te argenti pondus et auri Furtim defossā timidum deponere terrā? Hor. S. 1, 1, 42: per infrequentiam furtim senatusconsultum factum, Liv. 39, 4, 8: nunc in Aristippi furtim praecepta relabor, Hor. Ep. 1, 1, 18: furtim magis quam bello Marsacos incursabat, by stealthy incursions, Tac. H. 4, 56 fin.: furtim et per latrocinia ad honores nituntur, Sall. J. 4, 7: furtim et celeritate proelium vitare, id. H. Fragm. 1, 65 Dietsch.

        1. * (β) Poet., connected with a noun in the Greek manner: concubitusque tuos furtim, secret, clandestine intercourse, Tib. 2, 5, 53.