TWSI is software that produces lexical substitutions in context for over 1000 frequent nouns. It processes English text. This functionality is realized by a supervised word sense disambiguation system, which is trained by sense-labeled occurrences of target words. A classification model is trained for each word, and used to decide which sense an unseen occurrence most likely belongs to. Associated with senses are lists of substitutions, which are injected into the text using inline annotation.