1. Although it doesn't seem to make sense that this has anything to do with pro, "before" and polis, "city"; it is said to be from Greek then Latin, meaning "suburb", bee glue (from the fact that it was originally the name of a structure around the opening into the hive or "bee city").
2. It is defined in the Oxford English Dictionary as a red, resinous, aromatic substance collected by bees from the viscid buds of trees; such as, the horse-chestnut; used to stop up crevices and to fix the combs to the hives; bee-glue.