Between-Subjects Design refers to a research design in which different groups of participants are randomly assigned to an experimental condition (exposed to one or more experimental treatments) or to a control condition (not exposed to an experimental treatment ).
Other /More definition:
Between-subjects design refers to an experimental research strategy in which each research participant provides data for only one level of the independent variable or variables.
A research paradigm in which different experimental subjects participate in different experimental conditions.
an experimental design in which each subject is tested under only one level of each independent variable