hole
1. <electronics> In the hole model of current flow, the absence of an electron, e.g. in a semiconductor material. In the electron model, a hole can be thought of as an incomplete outer electron shell in a doping substance. Considering holes as positive charge carriers is a useful abstraction.
2. <security> A security vulnerability, particularly one which allows an attacker to gain unauthorised access to a system (by analogy with a hole in a wall).