Real Dictionary

double-blind
adjective: A double-blind study or experiment compares two groups of people, one of which is being tested while the other is not. Neither the people doing the testing nor the members of the two groups know which group is being tested.

double-blind in American English
designating or of a technique used to test objectively the effects of a drug, course of treatment, etc. in which neither the subjects nor the researchers know during the testing who is actually receiving the drug, treatment, etc. and who is not, as in an
adjective: of or pertaining to an experiment or clinical trial in which neither the subjects nor the researchers know which subjects are receiving the active medication, treatment, etc., and which are not: a technique for eliminating subjective bias from the test re

double-blind in British English
adjective: of or relating to an experiment to discover reactions to certain commodities, drugs, etc, in which neither the experimenters nor the subjects know the particulars of the test items during the experiments