the.com/wall of silence

means A collective, deliberate refusal by a group to share information, usually to protect themselves or each other from blame.

from A straightforward metaphor rather than a coined term with a traceable inventor: 'wall' for an impassable barrier, 'silence' for the refusal to speak, fused into one phrase. It gained its modern edge largely through police, military, and organized-crime contexts in the 20th century — describing witnesses, officers, or members who close ranks and give investigators nothing. The image works because it borrows the oldest trick in language: turning an abstract social act (withholding truth) into something solid you can picture, like hitting a brick wall when you ask a question.