Hi-
I'm new to poker and have a somewhat dumb question on terminology. I'm ready a Sklansky book and he has said a couple of times that you should rarely (~ 1 in 500 hands) cold call a raise.

What the heck is a "cold call"? Can someone give me an example or two? I've searched on-line for an answer, but the results are contradictory and/or confusing.
Thanks,
Mark