Lewis & Short

umbrācŭlum, i, n. [umbra] (any thing that furnishes shade).

  1. I. Lit., a shady place, bower, arbor, Varr. R. R. 1, 51, 2; Cic. Fragm. ap. Macr. S. 6, 4; Verg. E. 9, 42.
    1. B. Transf., a school: in solem et pulverem, ut e Theophrasti doctissimi hominis umbraculis, Cic. Brut. 9, 37: ex umbraculis eruditorum in solem atque in pulverem, id. Leg. 3, 6, 14.
  2. II. A sunshade, parasol, umbrella, Ov. F. 2, 311; id. A. A. 2, 209; Mart. 14, 28, 1; Tib. 2, 5, 97; Amm. 28, 4; App. Mag. p. 315, 16.