primary /prī″mərē/ [L, primus, first] , 1. first in order of time, place, development, or importance. 2. not derived from any other source or cause, specifically the original condition or set of symptoms in disease processes, such as a primary infection or a primary tumor. 3. (in organic chemistry) referring to the first and simplest compound in a related series, formed by the substitution of one of two or more atoms or of a group in a molecule. Compare secondary, tertiary.
