No-comment Definition

interjection

(idiomatic) An "official" refusal to relay any further information, used for example in response to a question by a newspaper reporter or police officer.

The district attorney said, "No comment," when the reporter asked if he knew the identity of the murder suspect, for fear that he (the culprit) might be a flight risk.

Wiktionary

(idiomatic) A refusal to say the obvious impolite retort.

Wiktionary