1. An authoritative order or decree; an edict.
2. A proclamation of a czar in imperial Russia.
George Will used the word in a widely read opinion piece.
...Bush is right in framing his new policy as a ukase to Iraq's government: We are buying you time, and not much of it, for you to dash to competence concerning security matters. Bush's policy probably will not succeed, but at least we will know what were the parameters of the possible, given the government produced by those Iraqi elections that once were the source of so much U.S. confidence.