Lewis & Short

perplexābĭlis, e, adj. [perplexor], perplexing: verbum, obscure, ambiguous, Plaut. As. 4, 1, 47; cf.: quod aliud audiatur, aliud sentiatur, Non. 151, 31.
Adv.: perplexābĭlĭter, in a perplexing manner, perplexingly: perplexabiliter earum hodie perpavefaciam pectora, Plaut. Stich. 1, 2, 28.