Hi Irulan
Peleton is the French the name give to the main group or bunch during any type of road races.
Riding in the peleton can be pretty hairy at times - the pro's can get up to speeds of 35 mile per hour on the flat and if you're in the middle you just get swept along. Never had the gutts to ride in a big group so far, but I guess is must be pretty exhilarating. They ride ridiculously close to each other so everyone has to know what they're doing - just the slightest twitch or over-reation and the whole lot can come crashing down, with bikes and bodies all over the place.
Very sorry to hear about your friends daughter. I hope she's now on the mend.