Click
One detent of adjustment on a scope turret. Each click moves the reticle a known angular value, typically 0.1 mil or 1/4 MOA.
“Up four clicks” = 0.4 mil up on a mil scope, or 1.0 MOA up on a quarter-MOA scope. The shooter speaks in clicks during a string because it’s faster than reading the dial markings.
A scope that “tracks” honestly moves exactly its labeled value per click, across the entire elevation range, repeatably. Verifying tracking on a tall target is standard practice when commissioning a new scope.