blip

1. (Radar) a spot of light on a radar screen, showing the position of a reflecting surface, such as an airplane or ship.
2. a short upward or downward deviation from a trend line on a graph, especially in a plot of some variable, such as an economic variable, against time; as, a brief blip upward in the unemployment rate.
3. something small or insignificant.
4. a brief interruption in the continuity of a recorded or transmitted signal; as, there is a blip on my CD of Beethoven's ninth.

this sense is also used metaphorically to mean a barely perceptible object; , Kennedy's candidacy was a mere blip on Humphrey's radar screen until he won the West Virginia primary. This is the probably origin of sense 3.