(a.) So tightly fitted as to preclude the escape of gas; impervious to gas.

ballproof bombproof bulletproof burglarproof close compact corrosionproof dampproof dustproof dusttight fast fire-resisting fireproof firm flameproof foolproof gasproof gastight hermetic hermetically sealed holeproof impervious to leakproof lightproof lighttight noiseproof oilproof oiltight proof proof against punctureproof rainproof raintight resistant rustproof sealed shatterproof shellproof shut fast smokeproof smoketight snug soundproof staunch stormproof stormtight tight water-repellant waterproof watertight weatherproof windproof windtight