1. A method comprising: receiving, from a user, a visual reference to a specific entity in a known domain, where an identity of the specific entity is unknown; extracting a visual context from a domain-specific training data associated with the known domain; determining the identity of the specific entity using the visual reference in combination with at least one of a speaker history, the visual context, and speaker preferences; and generating a text expression referring to the specific entity based on the identity of the specific entity.