1) Occupational, sometimes for the craftsman who made bow-strings.
1359-60 Thomas le bower, Thomas le stringer, York
1420 in arte quadam que vocatur stryngercrafte ... et quod lez strynges pro arcubus qui inventi erunt defectivi, York. Away from towns and cities the stringer was more likely to be an iron-worker, a smith or nailer who worked at the string-hearth: c.1270 Thomas called le Strenger, Bramley
1379 Johannes Strynger, nayler, Thornhill.