Английский Этимологический словарь - staunch (v.)

- early 14c., from O.Fr. estanchier "cause to cease flowing, stop, hinder," from estanche "firm, watertight," fem. of estanc "dried, exhausted, wearied, vanquished," from V.L. *stanticare, probably from L. stans (gen. stantis), prp. of stare "to stand." Adjective sense of "strong, substantial" first recorded 1455.