1. A computer-implemented method of automatic speech recognition, comprising: generating a static vocabulary weighted finite state transducer (WFST) having nodes connected by arcs to propagate at least one token through the static vocabulary WFST and at least one dynamic vocabulary trigger marker at at least one of the arcs; propagating a token through at least one dynamic vocabulary WFST upon the at least one token reaching the trigger marker; propagating a token through at least one grammar WFST having at least one dynamic vocabulary class marker that indicates a type of dynamic vocabulary and is associated with the dynamic vocabulary of at least one of the dynamic vocabulary WFSTs with a propagating token; and providing a hypothetical word or phrase depending, at least in part, on the WFSTs and comprising terms in the static vocabulary, dynamic vocabulary, or both vocabularies.