35. A computer-implemented method comprising: receiving a multi-term synonym phrase that is a candidate synonym for a multi-term query phrase; and determining, using one or more computers, that each term of the query phrase is a lexical synonym of a corresponding term of the synonym phrase or shares meaning with the corresponding term of the synonym phrase; in response to determining that each term of the query phrase is a lexical synonym of the corresponding term of the synonym phrase or shares meaning with the corresponding term of the synonym phrase, using the query phrase and the synonym phrase to improve a synonym mapping between a particular term of the query phrase and a term of the synonym phrase that corresponds to the particular term.
50. The method of claim 35 , wherein a synonym for a query term or query phrase is a term or phrase which is substantially similar in meaning and/or produces query results similar to query results produced by the query term or query phrase.