thoroughgo

The story

1. Old English · inherited fromþurhgān“to go through, go over, pass through, pierce, penetrate, permeate, pervade”
2. Middle English · inherited fromthurhgon
3. English todaythoroughgo

From Middle English thurhgon, from Old English þurhgān (“to go through, go over, pass through, pierce, penetrate, permeate, pervade”), equivalent to thorough- + go. Cognate with Dutch doorgaan (“to go on, continue, go through, proceed”), German durchgehen (“to go through, pass through”).