A method and apparatus for matching equivalent words across languages takes advantage of a set of rules that are built from a user-defined language specification (UDLS), which may be open source and customizable by a language expert. The UDLS is used to build a customer language library (CLL) that includes a list of consonants, a list of vowels, and rules defining phoneme equivalencies across two languages. The CLL is used to match equivalent words by both two-set and three-set matching to not only increase the number of true matches (i.e., overall accuracy), but also improve recognition of variations in a manner that is not language specific.