Mirror ball?
I know these things predate disco by decades. All you have to do is watch dance hall movies made before the Disco era to see them.
So what are they?
I even called a party supply place and asked what those shiny balls that hang from the ceiling with mirror-looking thingies on them are called. Answer: disco ball.
I vaguely recall an even better name than “mirror ball” that had the same basic structure as “rotogravure” (as in Easter Parade) but I know that’s not it, either.
Anybody?
My dictionary has an entry under “mirror ball”, but doesn’t say anything about there being another, more correct, name. Sorry.
How about you make one up? From the Greek, maybe katoptroglobe? Or, for a more Latin flavour, speculosphere? 
I’ve only seen “mirror ball” and “glitter ball” in use aside from “disco ball”, myself.
I sort of favor “Sawalha Sphere”, but that’s real obscure…
Thanks for the suggestions, r_k and Dogface, but “disco ball” works as a reasonable term when you’re trying to get the point across, as in, “Yo! Watch Out! Disco ball!” or “look at the girl under the disco ball, the one with three feet.”
It’s just one of those Jeopardy! type answers I want to be ready for.
Speaking of which, I was thinking a good Jeopardy! category might be “Jeopardy! clues that were used before and nobody ever got them.”
On with the show…
The folks at NASA seem content to use the term “mirror ball”. From this page, http://nssdc.gsfc.nasa.gov/spacewarn/spx574.html
NASA does like to use the scientific jargon, so if they can’t come up with something fancier than “mirror ball”, I’m not sure such a term exists.
Thanks, chukhung. You make a good case for “mirror ball.”
Whatever this other word is/was that I’m thinking I remember may just be something somebody else made up.
I’ve heard (and prefer) the term “mirror**ed[/ed] ball.”
What a dolt I am. Once more, that’s:
I’ve heard (and prefer) the term “mirrored ball.”
Zeldar, is the word you’re thinking of “lenticular”?
postcards
I looked that up after seeing your suggestion and it doesn’t appear to be what I’m remembering I heard/read some time ago.
Thanks, though.
Z
Disco Ball, Disco Ball,
On the ceiling
Can you make my dance appealing?
My parents refer to it as ‘Tango Ball’. As they were born in the 30’s, it might serve as an indication about what was used before the disco era.
“Mirror ball” seems to the the term mused by companies that sell them, though some do both (to make sure not to miss any customer, I guess):
here
and here (UK) and here
This was apparently invented in the 1930’s or '40’s, an early example of one can be seen in the movie Casablanca, starring Humphrey Bogart, from 1942.
I prefer mirrored ball to mirror ball, too. (One of which is the correct generic name.) Unfortunately a Google fight reveals that mirror ball is about 15 times more popular. And understandably since the d to b sound is difficult to say and quickly dropped in common speech.
Do it.
I had one named Keith. Does that help?
No, it doesn’t help.
Do you have anything useful to contribute?