stonewall
v.v. to refuse to give any information or help to someone who is asking for it. You use this when someone is being very secretive or difficult to deal with.
v. to refuse to provide information or assistance, often in a way that is deliberately obstructive or evasive.
The politician tried to stonewall the reporters.
The company's lawyers decided to stonewall the investigators to avoid revealing any sensitive data.
Despite the mounting pressure from the committee, the executive chose to stonewall, citing national security concerns as a justification for his silence.
From Middle English stonwal, stone wall, stanewalle (“wall made of stone”), from Old English stānweall (“stonewall”), equivalent to stone + wall. The alcoholic drink (sense 3) was perhaps named thus because its effect was as potent as running into a stone wall.
Apparently a corruption of stone cold.