S Your new gas furnace may have been installed in one of two. ways, as a direct-vent (2-pipe-Fig. 2) application or as a. non-direct vent (1-pipe-Fig. 3) application. S In a direct-vent (2-pipe) application,your furnace uses air. from outside the home for combustion and ventsflue gas to the. outdoors.
For the biological concept, see Anti-predator adaptation. A defence mechanism is an unconscious psychological mechanism that reduces anxiety arising from unacceptable or potentially harmful stimuli. Sigmund Freud was one of the first proponents of this construct.
Princeton's WordNet(0.00 / 0 votes)Rate this definition: 1  defense mechanism, defense reaction, defence mechanism, defence reaction, defense, defence(noun) (psychiatry) an unconscious process that tries to reduce the anxiety associated with instinctive desires. defense, defence, defending team(noun) (sports) the team that is trying to prevent the other team from scoring.