·superl Apt to disclose secrets; tattling; not close.
II. Leaky ·superl Permitting water or other fluid to leak in or out; as, a leaky roof or cask.
Apt to blab; one who cannot keep a secret is said to be leaky. ...
Dictionary of The Vulgar Tongue by Francis Grose
The state of a ship admitting water, and a cask or other vessel letting out its contents. ...
The Sailor's Word-Book