þaírh-

Part of speech: prefix
occurs prefixed to several Goth v-s indicating 1. the motion through something, overcoming obstacles, etc; þaírhgaggan “to go through; to pierce through”; 2. completion of the action: þaírhwakan “to stay awake; to keep watch throughout”; þaírhwisan “to remain throughout; to stay, continue”
Etymology
[← þaírh prep; OE ðurh-, þurh-; O Fris thruch-; O Sax thurh-; Dt door-; OHG duruh- (Mod G durch-)]