1. Of or pertaining to a unit or units; relating to unity; as, the unitary method in arithmetic.
2. Of the nature of a unit; not divided; united.
(Science: chemistry) Unitary theory, the modern theory that the molecules of all complete compounds are units, whose parts are bound together in definite structure, with mutual and reciprocal influence on each other, and are not mere aggregations of more or less complex groups; distinguished from the dualistic theory.