α. Old English þurh-arn (3rd singular past indicative), Old English ðurh-arn (3rd singular past indicative), Old English þurh-yrnan, early Middle English þorh-earnde (past tense), early Middle English þorh-harnde (past tense), early Middle English þorh-hearnde (past tense), early Middle English þurh-arnde (past tense), early Middle English þurh-arnde (past tense), early Middle English þurh-ærne, Middle English þurch-ernne.
β. Middle English thorou-ran (3rd singular past indicative), 1500s thorow-runne, 1600s thorough-run.