Lewis & Short

in-callĭdus, a, um, adj., unskilful, incapable, simple, stupid: servus non incallidus, i. e. shrewd, knowing, Cic. Clu. 16, 47: non incallidi homines, id. Inv. 1, 3, 4: incallidus alioqui et facilis juventa, Tac. A. 3, 8: judex formae, incompetent, Sabin. Her. 3, 55; cf.: fuit in jure non incallidus, Capit. Macrin. 13.
Adv.: incallĭdē, unskilfully: in his tribus generibus non incallide tergiversantur, Cic. Off. 3, 33, 118: opposuisse hoc Tullianum, Gell. 12, 13, 19: conquirere, id. 7. 3, 45.