On UNIX-like systems, a positive floating-point number that expresses how busy a the CPU is. Theoretically, a value of 0 is completely idle, a value of 1 is the maximum work that a single-processor computer should do, and anything higher than that is the product of some sort of incantation calculating how abusive you are to your server. Load averages are most commonly seen in the output of the uptime command.

Example:

$ uptime
 12:34am  up 51 days,  6:12,  1 user,  load average: 7.62, 7.64, 6.68

(Yes, I was mean to that server... Running 3 mp3 encoders and a seti@home is not good for a pentium 75. At least I have it on a UPS, so it's uptime is way better than my workstations...)