Yotz was a Hynerian exclamation used like "hell", "damn", "heck", "bugger". It also means "god". Rygel once used the term in a god context when he exclaimed "By the yotz!" in relief when Moya was relocated ("Lava's a Many Splendored Thing"). Also, he said "For yotz sake" which presumably means "for god's sake" several times in the series.