Flak and Knocking

Flak noun - Artillery designed to shoot upward at airplanes.

Knocking and flak are semantically related in brickbats topic. In some cases you can use "Knocking" instead a noun "Flak". informal substitute

Knocking noun - The sound of knocking (as on a door or in an engine or bearing).

Flak and knocking are semantically related in strong criticism topic. Sometimes you can use "Flak" instead a noun "Knocking".

Nearby Words: knock, knocked, knocker