[another-dave]

You say that, but "mechanically" in the dictionary gives "In a mechanical manner."

"Mechnical" gives "Of or relating to machines or tools."

"Machine" gives "A device consisting of fixed and moving parts that modifies mechanical energy and transmits it in a more useful form." and "A system or device for doing work, as an automobile or jackhammer, together with its power source and auxiliary equipment."

An ox & cart fits the bill for "machine" with that lens. Not sure it's a smart-alec workaround, any more than the likes of McVities arguing the biscuits vs cakes in court for Jaffa Cakes. Anything not defined is fair game.

[EliteGadget]

It is perfectly obvious to me and to the vast majority of people. That is why they didn't bother defining it further.

> An ox & cart fits the bill for "machine" with that lens

No it doesn't. I don't think you thought this through. The cart itself cannot do anything without something else acting on it. An ox is obviously not mechanical (it being an animal) which is what is propelling the cart. Therefore it is not mechanically propelled.

If it was a person a bicycle then would be more ambiguity. But it is commonly understood that a bicycle (excluding e-bikes which are mopeds) is not a "motor vehicle", because it is propelled by the rider.

[dredmorbius]

"Propelled" is the other term in that definition. A conveyance might be mechanical in the sense you describe without being propelled by a machine.

At the same time, an individual person being blown forward by a sufficiently large fan might meet the qualification of "mechanically propelled" without being in a mechanical conveyance per se.

But more generally, a vehicle plus a motor of some description would seem to meet the definition. ICE, steam, electric, spring-wound, whatevs.