(1) To separate, to set apart from others; that which is so treated. (2) To free of chemical contaminants. (3) In psychoanalysis, to separate ideas, experiences, or memories from the affects pertaining to them. (4) In group psychotherapy, a patient to whom others in the group do not respond. (5) Viable organisms separated on a single occasion from a sample taken from a host or culture system. (6), A population that for geographic, linguistic, cultural, social, religious, or other reasons is subject to little or no gene flow. SYN: genetic isolate. [It. isolare; Mediev. L. insulo, pp. -atus, to insulate, fr. L. insula, island]