leakproof

adj

1. Resistant to leaks; hermetic, sound; as of a dry cell battery.

   “1904, Institution of Mining and Metallurgy (Great Britain), Bulletin, Institution of Mining and Metallurgy (Great Britain) (1904), p. 22, "In mining work difficult laying conditions, limited space, and movements of the ground, all combine to make the installation of a leakproof main with ordinary joints a very difficult matter."”

   “1929, Victor Wilfred Pagé, Modern Aviation Engines: design-construction-operation and repair, […], Norman W. Henley Publishing Company (1929), p. 1589, "Leakproof tanks shall be provided on all airplanes for service use unless the tanks are completely protected by armor."”

   “1967, Edward Locker Delmar-Morgan, Maintenance of Inboard Engines, Newnes (1967), p. 115, "There are two subdivisions in the flashlight dry cell range, the ordinary cheap one and the better-quality leakproof cell."”

verb

1. (transitive)To make resistant to leakage.