What exactly is "reversed" in the reversed electrical polarity term?

That's a hard one. I'll try to answer it with two different examples:

1) A radio requires 12 V applied to the + and - pins. i.e + of the battery to + of the radio and - of the battery to - of the radio. When + of the battery is applied to - of the radio and - of the battery is applied to + of the radio, the polarity has been reversed. The radio may or may not be destroyed.

2) A DC motor is marked + and -. A reversing switch is installed. When the polarity of the source is reversed by the switch, the motor travels in the opposite of the direction shown in the specifications. This type of "reversed polarity" is non-destructive.

So the definition is that the source is connected in the opposite of the intended or specified direction. This reversal may or may not be destructive.

Reversed Polarity is More Electronic term than Electrical, as it involves DC voltages.
Like KISS says, a DC motor will go reverse direction with reverse polarity.
Reversing line and neutral on AC motor will still rotate same direction.
If a Speaker polarity is not observed, then speakers can be "out of phase"
Speakers see AC voltage, but if out of phase, one speaker will be pushing out, with other speaker pulling in. Plus from amp needs to go to plus on all speakers.

In the world of typical AC electrical wiring it means that the hot and neutral are reversed. This can be at a fixture, appliance or just at a receptacle.
Effectively it makes no difference. From a safety standpoint is make a BIG difference.

I suspect you are referring to a general receptacle when you ask this. Did this term come from a home inspector?

askformeHLK:

Can you comment as to what prompted you to ask the question?

We heard some comments about AC, DC and intensional and destructive.

Household AC in the US is also defined as reversing it's polarity 120 times a second when referenced to a zero volt baseline.

Can I reverse polarity on a battery golf cart motor and make it run the motor the opposite direction when going forward. The motor makes a noise going forward but when in reverse the motor is quiet.

It should reverse the Motor fine, Transmission may be an issue.
Do you plan on driving forwards?