The story
- Proto-West Germanic*buþlijan
- Old Englishbytlan
- Middle Englishbilden
- Middle Englishbildere
- English todaybuilder
From Middle English bildere, byldere, from bilden + -ere. By surface analysis, build + -er. Compare Old English bylda, bytla (“hammerer, builder”).
Etymology from Wiktionary, CC BY-SA 4.0.