The story
- Proto-Germanic · inherited from*þadrê
- Old English · inherited fromþider
- Middle English · inherited fromthider
- English todaythither
From Middle English thider, from Old English þider, an alteration (probably by analogy with hider (“hither”)) of earlier þæder (“to there”), from Proto-Germanic *þadrê.
Etymology from Wiktionary, CC BY-SA 4.0.