18. A memory device containing computer-executable instructions, the memory device comprising: one or more instructions that receive a search query; one or more instructions that identify an implicitly defined semantic structure associated with terms in documents, where a plurality of rules are associated with the implicitly defined semantic structure, and where the semantic structure includes a list having a header and a plurality of items associated with the header; one or more instructions that determine a semantic-based distance relationship between a first term and a second term within the list; one or more instructions that select one of the plurality of rules, as a selected rule, based on the semantic-based distance relationship between the first and second terms within the implicitly defined semantic structure; where a first rule of the plurality of rules is selected when the first term is located in one of the plurality of items and the second term is located in a different one of the plurality of items, where a second rule of the plurality of rules, different than the first rule, is selected when the first term is located in one of the plurality of items and the second term is located in the same one of the plurality of items, and where a third rule of the plurality of rules, different than the first rule and the second rule, is selected when the first term is located in the header and the second term is located in one of the plurality of items; one or more instructions that determine, using a function based on the selected rule, a distance value for the first and second terms, where the function differs based on whether the selected rule corresponds to the first rule, the second rule, or the third rule; one or more instructions that rank the documents for relevancy to the search query based on the distance value; and one or more instructions that present the documents in an order influenced by the ranking.
18. A memory device containing computer-executable instructions, the memory device comprising: one or more instructions that receive a search query; one or more instructions that identify an implicitly defined semantic structure associated with terms in documents, where a plurality of rules are associated with the implicitly defined semantic structure, and where the semantic structure includes a list having a header and a plurality of items associated with the header; one or more instructions that determine a semantic-based distance relationship between a first term and a second term within the list; one or more instructions that select one of the plurality of rules, as a selected rule, based on the semantic-based distance relationship between the first and second terms within the implicitly defined semantic structure; where a first rule of the plurality of rules is selected when the first term is located in one of the plurality of items and the second term is located in a different one of the plurality of items, where a second rule of the plurality of rules, different than the first rule, is selected when the first term is located in one of the plurality of items and the second term is located in the same one of the plurality of items, and where a third rule of the plurality of rules, different than the first rule and the second rule, is selected when the first term is located in the header and the second term is located in one of the plurality of items; one or more instructions that determine, using a function based on the selected rule, a distance value for the first and second terms, where the function differs based on whether the selected rule corresponds to the first rule, the second rule, or the third rule; one or more instructions that rank the documents for relevancy to the search query based on the distance value; and one or more instructions that present the documents in an order influenced by the ranking. 21. The memory device of claim 18 , further comprising: one or more instructions that locate explicitly defined semantic structures.