1. A method in a computer system, the method performed in a lexical knowledge base derived from one or more corpora, the lexical knowledge base comprising a network of nodes each representing a word occurrence in the corpora, the lexical knowledge base having word subgraphs each corresponding to one word and containing text segment subgraphs derived from text segments containing the word, the method characterizing the sense of an occurrence of a polysemous word represented as a node of the lexical knowledge base and comprising the steps of: selecting a word subgraph of the lexical knowledge base corresponding to a first word; identifying within the selected word subgraph a first node representing a first occurrence of a second word, the first node having no word sense characterization; identifying within the selected word subgraph a second node representing a second occurrence of the second word, the second node having a word sense characterization; and copying the word sense characterization of the second node to the first node.