Lewis & Short

umbrātĭcus, a, um, adj. [umbra],

  1. I. of or belonging to the shade, i. e. to retirement, seclusion, or leisure: homo, i. e. who loves to stay in the shade, an idler, lounger, Plaut. Curc. 4, 3, 24.
  2. II. Esp., retired, private, contemplative (opp. forensis): Epicureorum delicata et umbratica turba, Sen. Ben. 4, 2, 1: solitaria et velut umbratica vita, Quint. 1, 2, 18 Zumpt N. cr. (al. umbratili): doctor, i. e. one who teaches at home, a private tutor, Petr. 2: litterae, composed in one’s study, Plin. Ep. 9, 2, 3: negotium, that is attended to at home, Gell. 3, 1, 10.