1. A computer program product for determining a similarity of databases, the computer program product comprising: a computer-readable storage device having computer readable program code embodied therewith, the computer readable program code comprising: (a) computer readable program code configured to select a first database and a second database from a plurality of databases that includes at least three databases; (b) computer readable program code configured to identify one or more terms found in the first database and found in the second database of the plurality of databases, wherein each term of the one or more terms is comprised of metadata of a structure of a database of the plurality of databases, and wherein terms of the one or more terms found in both the first database and the second database are one or more common terms; (c) computer readable program code configured to determine for a common term of the one or more common terms, a quantity of databases of the plurality of databases, in which a common term of the one or more common terms is found, wherein the quantity of databases of the plurality of databases in which the common term of the one or more common terms is found, constitutes a group, and wherein a range of groups includes each quantity of databases from a group of two databases to a group of a quantity of the plurality of databases; and (d) computer readable program code configured to determine a similarity score between the first database and the second database of the plurality of databases based on a tuple formed from the quantity of the one or more common terms found in each group of databases of the plurality of databases.