therethrough

The story

1. Proto-West Germanic · inherited from*þārþurhw
2. Old English · inherited from*þǣrþurh
3. Middle English · inherited fromther-thurgh
4. English todaytherethrough

From Middle English ther-thurgh, þerþurh, þærþurrh, from Old English *þǣrþurh, from Proto-West Germanic *þārþurhw, equivalent to there + through. Cognate with Old High German dārduruh.