n. 1 a light portable device for protection against rain, strong sun, etc., consisting of a usu. circular canopy of cloth mounted by means of a collapsible metal frame on a central stick. 2 protection or patronage. 3 (often attrib.) a coordinating or unifying agency (umbrella organization). 4 a screen of fighter aircraft or a curtain of fire put up as a protection against enemy aircraft. 5 Zool. the gelatinous disc of a jellyfish etc., which it contracts and expands to move through the water. umbrella bird any S. American bird of the genus Cephalopterus, with a black radiating crest and long wattles. umbrella pine 1 = stone pine. 2 a tall Japanese evergreen conifer, Sciadopitys verticillata, with leaves in umbrella-like whorls. umbrella stand a stand for holding closed upright umbrellas. umbrella tree a small magnolia, Magnolia tripetala, with leaves in a whorl like an umbrella. umbrellaed adj. umbrella-like adj.
[ It. ombrella, dimin. of ombra shade f. L umbra: see UMBRA ]