BCUT-descriptors (see definition below) based on a fusion of atomic properties such as polarizability and charge distribution, and on molecular connectivity, which together relate to a molecule's ability to interact with a receptor.

Chemistry space-the concept that any one compound can be assigned a position in a multidimensional space, where each axis corresponds to a structure-related property. For example, an axis could represent the presence or absence of a chlorine substituent, or of an aromatic ring. The "distance" between compounds in chemistry space can be a representation of their similarity or diversity.

Descriptors-molecular properties related to structure or electronic characteristics such as polarizability, aromatic ring centers, and others. Descriptors provide a way of comparing and contrasting molecules in a combinatorial library.

Diversity-the concept of culling the most molecularly diverse set of compounds from a combinatorial library to pare the library down to a manageable size and increase the chances of discovering a potential drug candidate.

Fingerprint-a string of yes or no answers about a molecule's properties. These can correspond to the axes used in chemistry space, for example: aromatic ring? yes. bromine? no. These answers can be represented as zeros and ones in a bit string, or fingerprint, unique to that compound. The fingerprints can then be analyzed for their diversity or similarity.

Metric-another term for descriptor.

Pharmacophore-a descriptor based on chemical "centers" with which a ligand molecule is likely to interact at a protein receptor site. These centers include hydrogen bond donors and acceptors, positive charge centers, aromatic ring centers, lipophiles, and acids and bases. A pharmacophore contains a set of centers and a specific geometry that is necessary for the ligand to bind to the receptor.

SAR and QSAR-acronyms for structure-activity relationship and quantitative structure-activity relationship. The terms refer to data that, as the names imply, relate a molecular structure to its biological activity. Used to augment the number of potential drug compounds once a promising lead has been identified.