People must have dealt with static electrical discharge for thousands of years; well before they began to understand the principles of electricity.
What would a static discharge be called in early modern English and old-English?
I don't have the answer to your question as to what "static electricity" was called before the term "electric" was coined, at the beginning of the 17th century:
- 1640s, first used in English by physician Sir TThomas Browne (1605-1682), apparently coined as Modern Latin electricus (literally "resembling amber") by English physicist William Gilbert (1540-1603) in treatise "De Magnete" (1600), from Latin electrum "amber, " from Greek elektron "amber" (Homer, Hesiod, Herodotus), also "pale gold" (a compound of 1 part silver to 4 of gold); which is of unknown origin. (Etymonline)
Nonetheless the issue is interesting and I think it may be constructive to provide some more details:
Long before any knowledge of electricity existed people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BC referred to these fish as the "Thunderer of the Nile", and described them as the "protectors" of all other fish.
Electric fish were again reported millennia later by ancient Greek, Roman and Arabic naturalists and physicians.....Patients suffering from ailments such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them. Possibly the earliest and nearest approach to the discovery of the identity of lightning, and electricity from any other source, is to be attributed to the Arabs, who before the 15th century had the Arabic word for lightning (raad) applied to the electric ray.
Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, could be rubbed with cat's fur to attract light objects like feathers. ***Thales of Miletos made a series of observations on static electricity around 600 BC, from which he believed that friction rendered amber magnetic.
Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber.
He coined the New Latin word electricus ("of amber" or "like amber", from ήλεκτρον [elektron], the Greek word for "amber") to refer to the property of attracting small objects after being rubbed.
This association gave rise to the English words "electric" and "electricity", which made their first appearance in print in Thomas Browne's Pseudodoxia Epidemica of 1646