The story
From will -st, the archaic second-person singular tense suffix.
Etymology from Wiktionary, CC BY-SA 4.0.
willst
Today it means: (archaic) second-person singular simple present indicative of will (Alternative form of wilt) Full definition →
Today it means: (archaic) second-person singular simple present indicative of will (Alternative form of wilt) Full definition →
From will -st, the archaic second-person singular tense suffix.
Etymology from Wiktionary, CC BY-SA 4.0.