11. A system for knowledge-enhanced speech recognition, comprising: a context stack configured to store one or more expected contexts associated with a natural language utterance; and a knowledge-enhanced speech recognition engine, wherein the knowledge-enhanced speech recognition engine includes one or more processors configured to: access the one or more expected contexts stored in the context stack in response to one or more active grammars in a context description grammar failing to completely match information associated with the natural language utterance; compare the information associated with the natural language utterance to one or more context specific matchers to determine a most likely context associated with the natural language utterance from the one or more expected contexts stored in the context stack; and use one or more grammar expression entries in the context description grammar to generate a command or request associated with the most likely context.
11. A system for knowledge-enhanced speech recognition, comprising: a context stack configured to store one or more expected contexts associated with a natural language utterance; and a knowledge-enhanced speech recognition engine, wherein the knowledge-enhanced speech recognition engine includes one or more processors configured to: access the one or more expected contexts stored in the context stack in response to one or more active grammars in a context description grammar failing to completely match information associated with the natural language utterance; compare the information associated with the natural language utterance to one or more context specific matchers to determine a most likely context associated with the natural language utterance from the one or more expected contexts stored in the context stack; and use one or more grammar expression entries in the context description grammar to generate a command or request associated with the most likely context. 14. The system of claim 11 , wherein the speech recognition engine is configured to dynamically constrain a vocabulary of words associated with a virtual dictation grammar to include one or more decoy words for out-of-vocabulary words based on one or more prior utterances that were successfully transcribed by the speech recognition engine.