Leak  —n. 1 a hole through which matter passes accidentally in or out. B matter passing through thus. C act of passing through thus. 2 a similar escape of electrical charge. B charge that escapes. 3 disclosure of secret information. —v. 1 a pass through a leak. B lose or admit through a leak. 2 disclose (secret information). 3 (often foll. By out) become known.  have (or take) a leak slang urinate.  leaky adj. (-ier, -iest). [low german or dutch]