From 千(ち) (chi, “thousand”) + 千(ち) (chi, “thousand”).
ちぢ • (chiji) ←ちぢ (tidi)?
ちぢ • (chiji) ←ちぢ (tidi)?-na (adnominal ちぢな (chiji na), adverbial ちぢに (chiji ni))