Tetracoordinate

Part of speech: adjective

Definitions

1. Describing an atom or molecule bonded to exactly four neighboring atoms or ligands in a coordination arrangement
2. Having four coordinating partners attached to a central atom, as in certain metal complexes and crystal structures
3. Characterizing a central atom surrounded by four directly bonded atoms or ligands within a chemical compound

Etymology: "Tetracoordinate" is a plain technical formation: "tetra-", from Greek "tetra" meaning "four", joined to "coordinate". The second part comes from Latin roots meaning "together" and "arrange" and in English gives the sense of something arranged or related with others in a set, most familiar from chemistry and crystallography, where it describes atoms or groups bonded to four neighbours. Combining the two produces an adjective meaning having four coordinates or four coordinating bonds. The prefix "tetra-" is the same Greek numeral seen in "tetrahedron" and "tetrarch", and it is attached to technical terms freely in modern scientific English. The word therefore belongs to the same family of coinages as "tetravalent" and "tetrahedral", built deliberately from existing parts rather than inherited from older usage.