exhaust plume of a jet engine

[Tyler]

Is word 2 spelled correctly?

[Charlene]

Yes, though there is a variation.

[Staley]

And the hint doesn't apply to the answer, but to an alternate name.

[Tyler]

After seeing the answer, I still don't get it.

[Staley]

It seemed odd to me, too, but the same article where I found the answer Charlene used (mach disk) listed alternate names (mach disc, mach diamond) and it was searching for diamond that led me to it.

[Tyler]

Thanks. I had mach diamond and mach disc - never occurred to me to try disk.