1. A method of specifying to a voice recognition system a set of valid utterances for interpreting voice-based queries for items within a domain of items, the method comprising: extracting phrases from at least some of the items within the domain; expanding each phrase into a set consisting of individual terms of the phrase and forward combinations of terms within the phrase, to thereby generate a set of utterances which includes both single-term and multiple-term utterances; incorporating at least some of the single-term and multiple-term utterances into the voice recognition grammar; and providing the voice recognition grammar to the voice recognition system.