Flak and Set-to

Flak noun - Artillery designed to shoot upward at airplanes.

Set-to and flak are semantically related In some cases you can use "Set-to" instead a noun "Flak".

Set-to noun - An often noisy or angry expression of differing opinions.

Flak and set-to are semantically related in disagreement topic. Sometimes you can use "Flak" instead a noun phrase "Set-to", if it concerns topics such as competition.