Lewis & Short

quā̆drāgēnārĭus, a, um, adj. [quadrageni], of or belonging to the number forty, consisting of forty, of forty: dolium, perh. holding forty congii, Cato, R. R. 105, 1: fistula, a forty-inch pipe, i. e. made of a plate forty inches in width, Vitr. 8, 7: numerum, Vulg. Deut. 25, 3: pupillus, of forty, i. e. forty years old, Sen. Ep. 25, 1.
As subst.: quā̆drāgēnārĭus, i, m., a man forty years of age: quadragenarium istum ad te voca, Arn. 2, 60.