Flicker-free is a term given to video displays, primarily cathode-ray tubes, operating at a high refresh rate to reduce or eliminate the perception of screen flicker.
Contrary to popular belief, modern LCD monitors are not flicker free, since most of them use pulse-width modulation (PWM) for brightness control.
As the brightness setting is lowered, the flicker becomes more noticeable, since the period when the backlight is active in each PWM duty cycle shortens.
The goal is to display images sufficiently frequently to exceed the human flicker fusion threshold, and hence create the impression of a constant (non-flickering) source.
Conversely, interpolation (which avoids judder and may create more fluid motion than in the original video) can instead cause blurring, particularly visible on fast scrolling text.