watertightsack
nounUK /ˈwɔːtətaɪt sæk/
US /ˈwɔtərtaɪt sæk/
A watertight sack is a strong bag that keeps water from getting in or out.
The campers packed their matches in a watertightsack so they would stay dry.
RELATED WORDS
OTHER MEANINGS
2. A sealed compartment on a boat that keeps water out.
The sailors stored the rope in the watertightsack below deck.
3. A protective cover for keeping electronics dry outdoors.
She dropped her phone into a watertightsack before the kayak trip.
4. A person who keeps secrets very well (informal).
You can tell him anything—he's a real watertightsack.