1. A method for ranking search results, comprising: receiving a query string; retrieving a plurality of search results that include a corresponding plurality of target strings that relate to the query string; segmenting the query string and each of the plurality of target strings; pairing segments in the query string with respective segments in the target strings to form a plurality of word pairs, wherein one word pair of the plurality of the word pairs comprises a segment from the segmented query string and a segment from one of the segmented target strings; retrieving a plurality of weights that correspond to the plurality of word pairs based on a mapping of word pairs and their respective weights, wherein a weight measures semantic correlation between words in a word pair; and determining a weighted word length based on the weights corresponding to each of the plurality of target strings, wherein determining a weighted word length for a first target string of the plurality of target strings includes determining a minimum weight corresponding to each segment of the first target string with respect to segmented words in the query string, wherein the minimum weight corresponding to a first segment of the first target string comprises a minimum weight selected from a plurality of weights corresponding to respective ones of a subset of the plurality of word pairs associated with the first segment and the segmented words in the query string; and ranking the plurality of target strings based on their respective weighted word lengths.