Reticule Bloom (or just Bloom) is a gameplay mechanic in many First-person shooter games. The reticule on screen to aim at another person, as you fire at them, becomes larger making the accuracy of the shot weaker with each time you shoot. The reticule will return to normal size and accuracy after a short period of time without firing the weapon. Occasionally external factors will have an effect on the reticule of the weapon, such as running.
The bloom was first demonstrated at the E3 2013 presentation on Destiny.