blip

n. 1. (Radar) a spot of light on a radar screen, showing the position of a reflecting surface, such as an airplane or ship. 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.
Syn. -- radar echo, radar target. [ WordNet 1.5 ]

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. [ PJC ]

3. something small or insignificant. [ PJC ]

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. [ PJC ]