See my comment above (I have a handicapped son ...) - I don't think that use of retard is offensive. The other common non-pejorative use that I can think of is talking about the timing of the spark igniting the fuel in your (gasoline) ICE.

Trucks and buses for continuous, smooth braking (which would require stepping on the pedal for an extended amount of time, but this is discouraged because brake pads wear out and/or lose grip when engaged for too long) use a mechanical or electric assisting device that has the same name: https://en.wikipedia.org/wiki/Eddy_current_brake

I think it's a Family Guy episode where the callout also gets called... names in reply to the announcement.

Is it RE-tard (noun) or re-TARD (command)?

Is that difference in stress universal across English dialects? I thought there were some dialects that stressed nouns and verbs with the same spelling in the same way.

Isn't this a special case, because isn't the noun actually just short for "retarded"?

Which I think just has one pronunciation.