Is it a "rocket engine" or a "rocket motor?"

[John Kemker]

Give him a break. I think he’s just a kid.

My apologies.

 

[John Taylor]

The shaft of an electric motor is not driven by moving parts, but by rapidly-shifting magnetic force.

A motor generator is basically a motor driven by an outside force to induce voltage thru the windings. So is this electric motor a motor?

 

[Jay Rairigh]

They are all motors, but not all engines.

An automobile motor is an engine, but a solid propellant rocket motor is not.

 

[Funkworks]

I want to play!

Motor:
- a machine that can convert energy into a movement that can be used for some purpose

Etymology:
Borrowing from Imperial Latin motor, ‘someone or something that moves’; from Classical Latin motus ‘moved’, past participle of movere, ‘to move’.​

Engine:
- a machine that is designed to convert power into motion

Etymology:
Borrowing from Anglo-French engin, ‘device’; from Classical Latin ingenium, ‘innate character’.​

Personally, I'd go with "reactor" as a short for "chemical reactor":

(Chemical) Reactor:
– a structure that is designed to contain chemical reactions

Etymology:
From react and -⁠or; from Classical Latin actum, ‘decision’, and actus ‘done’, past participle of agere, ‘to do (formerly: to push)’, with influence of Medieval Latin reactus, ‘done again’.​

... but people would look at me like , so I'll stick with "motor" since the purpose of the device is to "mo"ve something (that "mo" is what seals the deal for me).

"Engine" is not wrong, but it's broader.
"Device" is not wrong, but too broad.
"Thing" is so broad it doesn't help.