Their main purpose is to prevent the women from escaping.

And once it's in there it prevents the gas from escaping.

He moved over to the dungeon door to prevent anyone from escaping.

He had to prevent it from escaping back into its lair.

For example, tests showed the cement was not strong enough to prevent oil and gas from escaping.

"To prevent it from escaping with the secret of the shell."

The walls of the court are six feet high to prevent the dogs from escaping.

Others would go off to the right to prevent the insurgents from escaping.

Small tentacles around the mouth also help prevent food from escaping.

At one point, they even set a brush fire in the soldiers path to prevent them from escaping.