the thing that basically hides
this was your drug addict's basic way of dealing with problems, was using the good old Substance to blot out the problem.
Context
The scene's — and arguably the theme's — thesis, arrived at not as doctrine but as something that "dawned on him in force" watching a dead man make the fatal choice. Handed news that will get him killed, Fackelmann doesn't run; he beelines home to the Sterno and the twin hills of Dilaudid and nails his chin to his chest, because the addict's one move against any problem, including terminal danger, is to use the thing that makes the problem stop being felt. The definition lands as a reduction — craven, pathetic, a thing that hides — and it is devastating precisely because Gately reaches it by full Identification, seeing his own reflex in Fackelmann's corner.