8. A method for disambiguating lexemes in text-to-speech processing comprising: loading a set of disambiguation rules for use in a text disambiguation engine of a text-to-speech system, wherein the disambiguation rules include a plurality of entries that define usage senses for lexemes, wherein each usage sense for each of the entries comprises: at least one conditional statement that defines a sense of usage for a lexeme; and a significance indicator associated with the conditional statement, wherein the significance indicator defines a criteria for selecting an associated sense of usage and wherein the at least one conditional statement includes a context range specification, wherein the set of disambiguation rules includes a first conditional statement for determining a sense of usage of a lexeme as an acronym and a second conditional statement for determining a sense of usage of the lexeme as a word, wherein the first conditional statement and/or the second conditional statement distinguishes between the sense of usage of the lexeme as an acronym and the sense of usage of the lexeme as a word at least in part by requiring a specified word within a specified context range of words of the lexeme; identifying, by the text disambiguation engine of the text-to-speech system, an ambiguous lexeme in a text input string; obtaining, by the text disambiguation engine of the text-to-speech system, the entry in the disambiguation rules that pertains to the identified lexeme, wherein the entry comprises at least one usage sense; determining, by the text disambiguation engine of the text-to-speech system, an applicable one of said at least one usage sense for the identified lexeme based upon an evaluation of the disambiguation rules associated with said at least one usage sense; and in response to determining a usage sense corresponding to the lexeme used as an acronym, replacing the lexeme with a defined full text equivalent.
11. The method of claim 8 , wherein particular ones of the usage senses comprise an optional action expression, where each action expression is associated with the conditional statement, and wherein the action expression defines a set of programmatic actions to be executed upon a selection of the associated usage sense.