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Medical Dictionary


noun bar·ri·er \ˈbar-ē-ər\

Medical Definition of BARRIER

:  a material object or set of objects that separates, demarcates, or serves as a barricade—see blood-brain barrier, placental barrier
:  a factor that tends to restrict the free movement, mingling, or interbreeding of individuals or populations <behavioral and geographic barriers to hybridization>
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