Summary: The language used to describe technical domains like UNIX is filled with metaphor. An approach to metaphor, based on the explicit representation of knowledge about metaphors, has been developed. MIDAS (Metaphor Interpretation, Denotation, and Acquisition System) is a computer program that has been developed based upon this approach. MIDAS can be used to represent knowledge about conventional metaphors, interpret metaphoric language by applying this knowledge, and dynamically learn new metaphors as they are encountered during normal processing.