qdš / Semitic roots

1. Kiddush, from Mishnaic Hebrew qiddûš, sanctification, purification, from Hebrew qiddēš, to consecrate, sanctify, derived stem of qādaš, to be(come) holy, sacred.

2. Kaddish, from Aramaic qaddiš, holy, sacred, from qədaš, to be(come) holy, sacred (so called after the first words of the prayer: yitgaddalwə-yitqaddaššəmeh rabbā, may His (God's) great name be exalted and kept holy).