1. A method of annotating a text document, the method comprising: determining, by a computing device, a term of interest within the text document; searching a data structure comprising incongruous term pairs (t x , tt) determined from a controlled vocabulary for the term of interest appearing as a term tt, wherein the term tt is a linguistic head of a term t x of the incongruous term pairs (t x , tt); and annotating the term of interest with a meaning provided by the controlled vocabulary only if a term t x of the incongruous term pairs (t x , tt) associated with the term of interest in the data structure is not present within a predetermined textual distance of the term of interest in the text document.