>>I read yours as a comment on the spelling/pronunciation of the version of the word which I'd always heard it as.<<

Whew! Glad we cleared that up!

>>yet taking lacksadaisical (whichever form) to mean *rebukable is a new one to me.<<

In a way, I agree. I wouldn't have given that definition if I hadn't already followed the trail at dic.com. In terms of origins, that definition seemed apt, and the reason I offered it was that I wasn't satisfied with the notion that one could be both industrious and careless at the same time. One can, of course, not be industrious and also not be deserving of rebuke -- at least, I hope so; but the contexts in which lackadaisical is most often used, in my experience, is one in which someone is supposed to be doing something and doing it carelessly. I exclude such circumstances where point-of-view is of paramount importance, such as work slowdowns, or resistance to unethical orders and the like.