15. One or more non-transitory computer-readable storage media having stored thereon computer executable units that are executable to perform actions comprising: obtaining a query log of a search engine; determining a threshold of a ranking of queries in the query log; selecting a plurality of queries with rankings higher than the threshold; obtaining a first word and a second word from the plurality of queries; determining that a shortest edit distance between the first word and the second word is less than or equal to an edit distance threshold; determining whether both of the first word and the second word exist in a preset knowledge database; in response to determining at least the first word does not exist in the preset knowledge database, segmenting the first word to obtain one or more terms; and determining whether the one or more terms after segmentation exist in the preset knowledge database, in response to determining that the one or more terms after segmentation exist in the preset knowledge database, searching a smallest granularity type with a highest weight value for each of the one or more terms in the preset knowledge database; in response to determining that both of the first word and the second word exist in the preset knowledge database, finding the smallest granularity type with the highest weight value for each of the first word and the second word in the preset knowledge database; determining whether the two words have a same smallest granularity type with a highest weight value; in response to determining that the first word and the second word have the same smallest granularity type with the highest weight value, determining that the first word and the second word are synonyms; and in response to determining that the first word and the second word do not have the same smallest granularity type with the highest weight value, determining that the two words are non-synonyms.
15. One or more non-transitory computer-readable storage media having stored thereon computer executable units that are executable to perform actions comprising: obtaining a query log of a search engine; determining a threshold of a ranking of queries in the query log; selecting a plurality of queries with rankings higher than the threshold; obtaining a first word and a second word from the plurality of queries; determining that a shortest edit distance between the first word and the second word is less than or equal to an edit distance threshold; determining whether both of the first word and the second word exist in a preset knowledge database; in response to determining at least the first word does not exist in the preset knowledge database, segmenting the first word to obtain one or more terms; and determining whether the one or more terms after segmentation exist in the preset knowledge database, in response to determining that the one or more terms after segmentation exist in the preset knowledge database, searching a smallest granularity type with a highest weight value for each of the one or more terms in the preset knowledge database; in response to determining that both of the first word and the second word exist in the preset knowledge database, finding the smallest granularity type with the highest weight value for each of the first word and the second word in the preset knowledge database; determining whether the two words have a same smallest granularity type with a highest weight value; in response to determining that the first word and the second word have the same smallest granularity type with the highest weight value, determining that the first word and the second word are synonyms; and in response to determining that the first word and the second word do not have the same smallest granularity type with the highest weight value, determining that the two words are non-synonyms. 16. The one or more computer-readable storage media as recited in claim 15 , further comprising after determining that the first word and the second word have the same smallest granularity type with the highest weight value, determining whether a term in the first word or the second word respectively is changeable without changing a meaning of the first word or the second word respectively, in response to determining that the term in the first word or the second word is changeable, further determining that the first word and the second word are synonyms; and in response to determining that the term in the first word or the second word is not changeable, further determining that the first word and the second word are non-synonyms.