Leaky \Leak"y\, a. [Compar. {Leakier}; superl. {Leakiest}.] 1. Permitting water or other fluid to leak in or out; as, a leaky roof or cask; a leaky faucet. [1913 Webster] 2. Apt to disclose secrets; tattling; not close. [Colloq.] [1913 Webster] 3. (Genetics) Retaining some function; not completely inactivating the gene; as, substitution mutations are sometimes leaky; -- of mutations. [PJC]