From πΏπ- (us-) + π±πΏπ²πΎπ°π½ (bugjan).
πΏππ±πΏπ²πΎπ°π½ β’ (usbugjan) (perfective)
The variant form πΏππ±π°πΏπ·ππΉπ³π΄π³πΉ (usbauhtidΔdi) is typically viewed as a misspelling of πΏππ±π°πΏπ·ππ΄π³πΉ (usbauhtΔdi), perhaps by analogy with class 1 weak preterites such as πππ³πΉπ³π΄π³πΉ (rΕdidΔdi).