Medical Definition of passive
1a (1): lethargic or lacking in energy or will (2): tending not to take an active or dominant part <a passive spouse>b: induced by an outside agency <passive exercise of a paralyzed leg>
2a: of, relating to, or characterized by a state of chemical inactivityb: not involving expenditure of chemical energy <passive transport across a plasma membrane>
3: producing passive immunity <passive immunotherapy>
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